Ski-Doo Snowmobiles Forum banner
21 - 40 of 49 Posts

·
Registered
Joined
·
14,289 Posts
Ive had both the RKT 734 and a Dmax 770, hands down I preferred the 770, its a sweet running combo. I sold my 770 7 years ago and as of 2 weeks ago the guy who bought it says its been 100% trouble free and it still rips.

.
Long time Erick! Are you still sledding ? Glad to see you are still monitoring the site.
 

·
RS
Joined
·
3,087 Posts
When hill dragging my 700's I would stick a 500ss pipe on it. Was like adding a supercharger... but I wouldn't run it much more than the 500 ft we raced. Yet the 600 SDI pipe, 600 Etec and the SPI pipe for those engines worked fine for general riding with the ported 700s but are too tight for the 770.

As mentioned in the pipe thread I attached, TT670 and modvx used the duramax pipe on theirs modvx used the flat land 800 on his sled the first year. I have used the
particular pipe mentioned in that thread down here in the flatlands on both my summit and my 120 shorty 770's for 4 seasons in all temps that we experience here in Michigan.

Interesting re the Jaw's comments. Ha ha. I have a Jaws pipe for my 850 and have not yet installed it, still sitting in the original box un opened. Perhaps I should.
I like your plug choice. They are in my sleds too. I get the impression your dissatisfaction with the 770s is more to do with Dmax than the 770 it's self. Using Big John, my experience is always there and a simple text or phone call away. He has answered my calls and texts on Sundays and evenings all year long each and every year. And it is my experience that each and everyone of us nobs gets the same job. Which I am not so sure happens in other shops based on all my 700 porting experiences.
My experience was for sure related to the dmax and not the 770.

The Jaws is awesome the sled does have more noticeable power but jaws alows max rpm to raise a little. I was worried as a lot of times with pipes you lose top end or bottom end, this pipe has great torque and its smooth throughout.

I've geared down with a belt drive and have ibackshift clutching and the whole combo can lead to sore arms even in deep snow (FR 146 w/2.5 lug)

If I had more space and money to burn I'd get another 09 RS and make it a 770 from a repputal engine builder. Missed that sled, I was going to rebuild it but my house burnt down a few days after I lost the motor, so I guess dmax got off the hook easy.. but I only had liability insurance and I lost out the most.
84bc8f167f6f896291a8dc9772ddbfcb.jpg


Sent from my SM-N975W using Tapatalk
 

·
Premium Member
Joined
·
11,990 Posts
Long time Erick! Are you still sledding ? Glad to see you are still monitoring the site.
Haven't thrown a leg over a sled since 2016 Don. Both me and my usual riding partner moved out of the snowbelt and haven't looked back. Last year we bought a second home on Lake Norman in Mooresville North Carolina and will be making our final move there in a couple of years. We do talk now and then about taking a trip someday and renting sleds, but for now I've got too many other irons in the fire.

I don't come here much, I'm pretty much out of touch with current sleds but I do check in now and then.

My 700 was basically the Dmax drop dome head, and I built the rest myself. I did struggle getting squish clearance right, DMAX was waaay out to lunch on what would clearance work with any level of reliability on pump gas. It took me 2 sets of pistons and 4 re-plated cylinders to get it right.
 

·
Registered
Joined
·
5,909 Posts
Haven't thrown a leg over a sled since 2016 Don. Both me and my usual riding partner moved out of the snowbelt and haven't looked back. Last year we bought a second home on Lake Norman in Mooresville North Carolina and will be making our final move there in a couple of years. We do talk now and then about taking a trip someday and renting sleds, but for now I've got too many other irons in the fire.

I don't come here much, I'm pretty much out of touch with current sleds but I do check in now and then.

My 700 was basically the Dmax drop dome head, and I built the rest myself. I did struggle getting squish clearance right, DMAX was waaay out to lunch on what would clearance work with any level of reliability on pump gas. It took me 2 sets of pistons and 4 re-plated cylinders to get it right.
Erick...if you are ever in Saskatchewan for the winter? feel free to look me up. Would be more than happy to take you out for a rip. There is seven sleds in the shop. Trust me i won't force you to ride the 380. :lol:

Good to hear from you. Been a long time like Don said. Thanks Brent.

Sorry guys i am way off topic.
 
  • Like
Reactions: djm

·
Registered
Joined
·
14,289 Posts
Haven't thrown a leg over a sled since 2016 Don. Both me and my usual riding partner moved out of the snowbelt and haven't looked back. Last year we bought a second home on Lake Norman in Mooresville North Carolina and will be making our final move there in a couple of years. We do talk now and then about taking a trip someday and renting sleds, but for now I've got too many other irons in the fire.

I don't come here much, I'm pretty much out of touch with current sleds but I do check in now and then.

My 700 was basically the Dmax drop dome head, and I built the rest myself. I did struggle getting squish clearance right, DMAX was waaay out to lunch on what would clearance work with any level of reliability on pump gas. It took me 2 sets of pistons and 4 re-plated cylinders to get it right.
I do recall the issues you had with getting the thing right. But I remember how happy you were when it was right. That pushed me into doing the first one I did with Big John, and then I was so happy with it, that I did a second one with him. Both are still running.

Hey how are you guys going to be able to make enough electrical power to charge 2 million electric cars and a few electric sleds in the future? Ha ha..or not your problem as you guys will be retiring before those requirements exist? I don't look forward to any of this stuff in the future. Assume their must be some plans to handle all of this stuff. A lake in North Carolina sounds pretty nice. I suspect it won't be covered in Ice like the one in front of the house here.

And what Brent says goes if you wanted to show up here, and darn, no 380 in the stable. But if I was going riding for a one time thing, it would be to the western mountains be it in the states or Canada.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #27 ·
Hey guys! Sorry for the delayed response my masters program and work have sucked up free time and then I picked up a boat last week!

Luckily I got to ride out the end of the season on our old trusty 06 500ss so I wasn't out of the game completely.

Where I'm at- motors still in the sled because it's still cold as bojangles here (no snow however) . Should be nicer next week finally so I can wash it down and tear her apart.

I still have the 700 parts they're getting listed after I pick up 770 parts tomorrow.

Made some good progress today parts wise.... I found a killer deal on a lot of 800ho parts that I'm picking up tomorrow- The parts are a set of 800ho jugs that need to be renicked so they'll be ported by BJ, a stock 800ho head (Thinking of getting an RKT head anyways) , rave valves, and an 800ho stock y pipe.

Other stuff-

-Still debating swapping in TM40's over the TMX's just not looking forward to replacing the whole intake system and not sure its worth it for mileage and oil injection. It sounds like tuning may be simpler but there's so much info on the 770 600rs swap I think this is a non issue.

-Decided on going with 25/45 gearing for a more trail friendly ride. I'm assuming this thing makes gobs of torque over the 600.

-Decided on going with a Camso Ice Storm Track for the 129" skid.

-Still trying to decipher what pipe to use it sounds like an 800r MXZ (flatland not summit) pipe is the ticket and it's very close to the Dmax unit in terms of stinger length and outlet (48mm) whilst being safe.

Questions that I can think of at this point---

Any reason to go with an aftermarket y pipe? Or is the stock good enough?
 

·
Registered
Joined
·
1,205 Posts
For the stock 800 head to be used. It would require machining. Better off to get a rkt or dmax head.
On the y pipe. Inspect it good. I see many with that are quite rusty under the heatshields. If its OK. No reason not to use.
I put a 146 storm on my sled this year. Very happy with it so far.
I'm not not one to ask on gearing...... I ran 25/49 on my 137. Even when I put the 860 in. But I think your choice would be good.
I tried alot of pipes back then. Most of the aftermarket and stock. I always ended back with the 800r flatland. The only one I felt was any better was the bmp 800r pipe but it was in a rev chassis. It worked excellent on my 827 also.
For the carbs. For most people I suggest converting to oil injection. And running the tm40s. Mostly for the aspect of not having to try to mix oil in on the trail. But if you are used to it. That would be a decision for you to make.
 

·
Registered
Joined
·
63 Posts
For the stock 800 head to be used. It would require machining. Better off to get a rkt or dmax head.
On the y pipe. Inspect it good. I see many with that are quite rusty under the heatshields. If its OK. No reason not to use.
I put a 146 storm on my sled this year. Very happy with it so far.
I'm not not one to ask on gearing...... I ran 25/49 on my 137. Even when I put the 860 in. But I think your choice would be good.
I tried alot of pipes back then. Most of the aftermarket and stock. I always ended back with the 800r flatland. The only one I felt was any better was the bmp 800r pipe but it was in a rev chassis. It worked excellent on my 827 also.
For the carbs. For most people I suggest converting to oil injection. And running the tm40s. Mostly for the aspect of not having to try to mix oil in on the trail. But if you are used to it. That would be a decision for you to make.
Hey thanks for the continued info and all the help! I picked up parts tonight so I'm heading in the right direction still- Grabbed a set of cylinders, raves, bolts, and a stock head that's pretty beat for $130 so not too bad. Tried grabbing the y pipe but like so many from those years it was literally cracked in two at the split.

I reached out to Daylan at DMAX today and he quoted me $450 for his y pipe and $500 for his pipe. Any point in going with his stuff over a 800ho BMP y pipe (which I think can be ordered with an EGT bung so that's a win as the 800r pipe is missing this) and a used xp 800r flatland pipe? The price would go from 1k for DMAX parts to maybe $400 for the BMP and stock 800r pipe.

Okay ill definitely be grabbing an RKT head then from BJ instead of messing with the stocker!

With regards to the carb convert my only worries are about the relocating of the sensor in my airbox and the wiring off the 800r carbs that needs to be dealt with. More than likely I will just bite the bullet and tear off the whole intake off then and put the OEM summit box pipe and stuff on using 800r boots reeds and carbs. I have no preference in all honesty but not mixing on the trail while I make the group wait would be nice.

Any links or info on the carb swap and what's required? Through my searching on doo talk etc I couldn't find too much for info. Just curious If I can use the stock throttle on the bars and just pick up the 800r cables oil pump, reservoir, hoses etc.

Should be all set in the gearing and track department for where I currently ride then. If I hate the 25/45 I can always swap right back to the 25/49 I have the full set of gears and chains for both setups.
 

·
Registered
Joined
·
14,289 Posts
Hey guys! Sorry for the delayed response my masters program and work have sucked up free time and then I picked up a boat last week!

Luckily I got to ride out the end of the season on our old trusty 06 500ss so I wasn't out of the game completely.

Where I'm at- motors still in the sled because it's still cold as bojangles here (no snow however) . Should be nicer next week finally so I can wash it down and tear her apart.

I still have the 700 parts they're getting listed after I pick up 770 parts tomorrow.

Made some good progress today parts wise.... I found a killer deal on a lot of 800ho parts that I'm picking up tomorrow- The parts are a set of 800ho jugs that need to be renicked so they'll be ported by BJ, a stock 800ho head (Thinking of getting an RKT head anyways) , rave valves, and an 800ho stock y pipe.

Other stuff-

-Still debating swapping in TM40's over the TMX's just not looking forward to replacing the whole intake system and not sure its worth it for mileage and oil injection. It sounds like tuning may be simpler but there's so much info on the 770 600rs swap I think this is a non issue.

xxx It is a mistake to not use the TM40's All the guys who fail these things seemed to use the TMX carbs. And the TMX tuning seems to be a big mish mash of opinions. But you have to do what you have to do. The TMX with V-Force reeds worked well for me. I never used any of the carb wiring. Hooked a pair of solenoid the wiring, hung the knock sensor in the air. Don't want the chance of timing being back off. I actually used the DPM on one of the two sleds. And on one I used the oil pump and oil injection and on the other I set up for premix and put a cover over the drive and hooked up the small tank from a 600 race sled. I only did this to see if I could see a difference in durability. So far I have not seen any.

-Decided on going with 25/45 gearing for a more trail friendly ride. I'm assuming this thing makes gobs of torque over the 600.

xxx Gears you can change daily.. I don't think any of us that seriously run one of these things would want to tell you what gears would work for you.. Depends on the track and what you are doing on a given days riding.

-Decided on going with a Camso Ice Storm Track for the 129" skid.

xxx That would work but I would recommend the Hurricane track, it is 2 ply and more efficient than the one ply ice storm. And why waste the extra quarter inch of hook up that the hurricane provides.

And use Woody's Triggers with Studboy Pro series double backers - they are light and act as more lug. The 770 has amazing torque.

-Still trying to decipher what pipe to use it sounds like an 800r MXZ (flatland not summit) pipe is the ticket and it's very close to the Dmax unit in terms of stinger length and outlet (48mm) whilst being safe.

xxx Well the summit 800 ETEC pipes on my sleds work super and if you use the 800R pipe you are giving up performance. neither of my Big John 770's have burnt down. Too much money and one of for the Duramax pipe and think if you were to check the dimensions on it, that they are pretty much what the 800 Summit pipes dimension were. The flatland pipe is larger in diameter than you need. If I ever get my old work laptop computer back with all my files on it.. and can give you the dimension. They are in a thread her on Dootalk but I can't find it using the search function. I got them from the guy who bought TT670's duramax pipe.

Questions that I can think of at this point---

Any reason to go with an aftermarket y pipe? Or is the stock good enough?

xxxx You know my opinion on this subject .. Remember we are talking 770, not 800 or 840 or 860 cc's. I would talk over these issues with BJ on the phone. If you become a customer of his, he will help you out a lot.

If I call him on a Saturday night or a Sunday morning when I am at a hill drag, and need a suggestion based on the snow conditions, he usually answers and gives me great directions. You can use the 600R race single pipe if you pull the stinger out of it. - that is a pain but can be done. I have one of those and I think that is what BJ recommended at the time. But sometimes I march to a different drummer and it works out. As I recall the summit pipes I used had the same stinger ID as the 600R single pipe with the stinger pulled. But all that stuff happened a few years ago when we were picking and choosing and building. RKT head is a good one, it is what is on mine. And BJ cut two sets of domes for me, one to run 91 Octane for general riding and one to run a bit higher octane for those special times. revx440HO is higher on aftermarket pipes than I am. And I have run a number of them. Did have a 600Etec SPI pipe that worked great on a ported 700 but the stock 600SDI pipe worked just as well. I had a thread on here with all the various pipe dimensions, but as stated, darned if I can find it with the search function. I found that one thread but it was not the one with stinger id's and lengths - and internal or external.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #31 ·
Thanks again for the awesome info!

TM40's it is I'll start grabbing stuff for the swap!

For the y pipe I'm grabbing a BMP 800ho unit for $200. All the stock ones I've looked at thus far are cracked or beat to heck. For safety sake might as well just grab a new unit.

As far as exhaust is concerned I found one of your older posts on here when searching for pipe stinger ID's. You said that the mxz flatland pipe is 48mm, the 800etec summit pipe is 43mm, the 600rs pipe with sleeve removed is 45mm.
Does the timing curve effect the pipe selection? I'm assuming this is true and if ones running a 600rs curve does that factor in to pipe selection as well? Hope I'm not overthinking this!

Track selection makes sense, I may just say screw it then and run the 2 ply 1.7 track that's already on the sled and stud if needed.
 

·
Registered
Joined
·
14,289 Posts
Thanks again for the awesome info!

TM40's it is I'll start grabbing stuff for the swap!

For the y pipe I'm grabbing a BMP 800ho unit for $200. All the stock ones I've looked at thus far are cracked or beat to heck. For safety sake might as well just grab a new unit.

As far as exhaust is concerned I found one of your older posts on here when searching for pipe stinger ID's. You said that the mxz flatland pipe is 48mm, the 800etec summit pipe is 43mm, the 600rs pipe with sleeve removed is 45mm.
Does the timing curve effect the pipe selection? I'm assuming this is true and if ones running a 600rs curve does that factor in to pipe selection as well? Hope I'm not overthinking this!

Track selection makes sense, I may just say screw it then and run the 2 ply 1.7 track that's already on the sled and stud if needed.
To be honest, I ran Dynoport Y pipes for the same reason you did.

Both of mine have 800R modules were reflashed my Ski-Doo at their center in Wisconsin to Doo's hot 700 curves with RPM limiters removed as they were originally done for the 700HO's (ported 600RS cylinders bored and renicked to 700 diameter) that I previously ran. I ran the 800R modules so I could have dpm and the knock sensors if I wanted to run them (both are hanging in the air at present time). and RER. Learned real quick that if you try to run the 600RS flywheels with the short twin tabs on them, with an 800R mpem that RER works but you are limited to 7200 rpm's (don't know why to this day) put 600HO/800R flywheels on with the longer trigger tabs and had unlimited rpm. I ran 8000 engine speed most of the time and I believe that or 8100 was recommended by BJ. I suspect the 600RS modules would work, but why not use 800R and have RER? 600RS stuff just gets you in trouble except for the hard parts like crankcase and shafts which is what I am using.

I would love it if you could post that thread with the pipe diameters - lost all that info with my laptop appropriation. Ha ha. learned a valuable lesson there, don't store all your good info on your work computer.. .You are a better searcher on Dootalk than I am. And my memory is not as good as the actual facts on paper at the time.

Yes, if you have the 1.75 snowcross track I would run that, and stud it appropriately.

As mentioned I am still running those two Summit 800Etec pipes. but now that you have flagged the ID's pulling the stinger out of the RS pipe might be a better choice. I have not had an issue with the summit pipes though. The 800R/Etec flat land pipe would be way safe. But why give up the power of a slightly tighter stinger if it doesn't hurt?

.
 

·
Registered
Joined
·
1,205 Posts
It is better to go with a complete known setup. If you are going with djm recommendation. I would follow it completely. I 100% agree with him on the carbs. Most that have had issues were kinda doing their own thing. Using parts that were available more than what may be best. I used to like to tinker more. Try every available option. Now I prefer more to take a good known combination and make more subtle changes.
I honestly preferred the 800r pipe. It would be nice to get one on the dyno and test them out. Keep in mind I was running different porting and timing. I may have to knock the dust 9ff and put one back together. Still have 738 and 770 and 800ss parts on my shelf. Along with dmax exhaust and several other pipes. Would just need to send a module out for programming. Been saving them for my son. But as of late have been considering just making a 700etec for him.
 

·
Registered
Joined
·
5,909 Posts
700 Etec...OK you have my attention. B)
 
  • Like
Reactions: djm

·
Registered
Joined
·
14,289 Posts
700 Etec...OK you have my attention. B)
Have often thought of this too! You'd want to do a ported one so you could really get something out of it. A 700HO ETEC would be the cats meow! Or a 770 ETEC; have often though 800 Etec injectors and program would be pretty close and require little tuning.
 

·
Registered
Joined
·
1,205 Posts
I have mocked up a 830 etec. 860 top with 600 crank.
Was looking into a 770 etec. Was somewhat stuck on keeping erave system happy. I had a couple different theories/ideas. But life happens....... never got back to it.
 

·
Registered
Joined
·
14,289 Posts
I have mocked up a 830 etec. 860 top with 600 crank.
Was looking into a 770 etec. Was somewhat stuck on keeping erave system happy. I had a couple different theories/ideas. But life happens....... never got back to it.
Life definitely happens, my Gen 4 belt drive got delayed when Ford terminated all of the contract engineers at the beginning of December 2020 (of which I was one). Going back to work after retiring is what jpaid for the toys.. Know others have had much tougher life happenings this past year so I am not complaining. Just won't be as quick as I would like to be.
 

·
Registered
Joined
·
5,909 Posts
The trouble with a 700 etec based off the 600HO is...there is no PCV for that model. The power commander is the way to go with the 860 etec and 872 etecs, from my experience.

The SPI fuel squirter box is the only way to fuel a mod 600HO etec. This system dumps in way to much fuel from my experience with them. Hard to lean it out for the full curve and does not inject fuel till 3500-4000 rpm. These Big bore etecs will run wipe open throttle on stock fuel curve. But they run lean as hell in the midrange with stock fuel curve. Even off /on throttle play they run lean with no fuel added in the midrange.

The Resistor trick only changes fuel on top end. It does not change the fuel curve in the midrange for some reason. Just passed experience messing with one on a Trygstad 872.

Maybe between the three of us we could make something work. with ideas and field experience. :lol:

Boring out the 600HO etec to 700 piston you lose the bridge on the rear transfer port.

Would be nice to keep or use the 600HO etec base cylinder... Erave system. The side barrels on the power valves help so much in low end grunt on these motors.
 
  • Like
Reactions: djm

·
Registered
Joined
·
14,289 Posts
The trouble with a 700 etec based off the 600HO is...there is no PCV for that model. The power commander is the way to go with the 860 etec and 872 etecs, from my experience.

The SPI fuel squirter box is the only way to fuel a mod 600HO etec. This system dumps in way to much fuel from my experience with them. Hard to lean it out for the full curve and does not inject fuel till 3500-4000 rpm. These Big bore etecs will run wipe open throttle on stock fuel curve. But they run lean as hell in the midrange with stock fuel curve. Even off /on throttle play they run lean with no fuel added in the midrange.

The Resistor trick only changes fuel on top end. It does not change the fuel curve in the midrange for some reason. Just passed experience messing with one on a Trygstad 872.

Maybe between the three of us we could make something work. with ideas and field experience. :lol:

Boring out the 600HO etec to 700 piston you lose the bridge on the rear transfer port.

Would be nice to keep the Erave system. The side barrels on the power valves help so much in low end grunt on these motors.
You can lean the whole curve on the 800ETEC with the PCV or richen it. A 700HO should demand pretty much the same fuel I would think, Maybe slightly different when it demanded it due to the shorter stroke. Use the 800Etec module with the PCV. and 800Etec injectors. . ????
 

·
Registered
Joined
·
63 Posts
Gah you guys are freaking me out now about the extent of the 770 build haha.

What exactly should I be running for timing then? 600rs curve or the 700 hot trail curve with the 770 build? Who can do the flashing work I'm not familiar with that side of it at all.

Likely I will be picking up a brand new 850 next year to ride most of the time and this sled will stick around as a ditch banger or deeper/fresh snow rides toy.

I agree 100% with sticking with the known combos versus going rouge and blowing motors etc.

This is the pipe ID thread- https://www.dootalk.com/forums/topic/1101466-pipe-options-for-770rs/
 
21 - 40 of 49 Posts
Top