help iqr 925 big bore can't fight through a wet paper bag..pipes? carbs?

[Old_Focker]

I posted in another tread and reaching out to anyone that can help.

I have a iqr that I put a big block ves 800 in and moded it to 925 with hot seats 925 kit. The kit works great in Minnesota, but I can't get her to go in the mountains. I believe the pipes are slp and the carbs are bored to 41.5-42mm. I know at this point I'm not running into a clutching or gearing problems as I have been everywhere on this. I can get pipe temp and have guages along with variflow that was recently added to keep adjusted in altitude. I run a 144 2.5 inch track.

I used to race and understand gearing and clutching. I understand that these motors need load. I don't understand why I can't get this little bastard to roar. I would give about anything to see it pull rrrrs and rip. Right now it is difficult to get a couple hundred above 7k on the digital tach. And you can tell it is not getting power.

I read in another tread that another person experienced this problem due to the port size in their stingers not being big enough. The best this sled ever runs in on the way out to play. Once I hit the hill I can't get it to pull rpms.

Any help is appreciated. I really want to get this sled to run. Next trip is Cooke third week in January. I would drive this sled out to someone and pay them to get it working. Or maybe I scrap it and sell everything I own and go to the fuely turbo.

Help

 

[BB454]

925

SLP pipes should be fine for elevation. Tighter pipes run better at elevation so even if they were tight they should run. What is your set up? Jetting, primary, secondary, and gears. Have you checked the timing? Are you running TPS and premium/standard ignition switch? If so any better one way or the other on the switch setting? When you did the 925, where did you put the static timing of the flywheel? What CDI? Stock?

Does Hot Seat have any suggestions?

The 800s run 10-60s out west and the 910s only 10-62s or 4s at elevation. If you are heavier than that, then there may be part of the problem.

 

[Old_Focker]

hot seat did all the work on timing and the cdi. No tps is run on this. I have no clue where they set that information. I do know that it runs fine hear. Just can't get it to run out west.

As far as gearing, I gear all my sleds around 2.15 to 2.2 out west for track speed and this motor should have no problem pulling that. I can ride wheelies with this longer than I could on my sport bike. Damn pancake out west.

Hot seat has no clue. They gave me what they would use and were way off. I believe I run 270 for jets out there. They wanted 390's. That is what I run at home hahah. The first time I took it out west I spent a day dropping jets and spark plugs until I got that figured out. We run 280-300 depening on temp and altitude on all of our 800s.

When leaving the cabins and the motor is still cold it runs great. Pulls the skis and rips. When I get to the hill and want to go up it wants to eat a snickers bar at the bottom. Think I may give it to my mom as a picture taking sled.

Anyone with problems with big bor carbs in elevation or slp pipes on a big bore big block ves???

 

[mountin fit]

air intake

what are you running for a intake? pods don't work well on this chassis without a LOT of venting, we always use a air box on this chassis and duct it to outside air. with the body work on this sled when you slow down the temps under the hood get very high and pods just suck hot air, try a couple of pulls with the side panels off and see if it helps. if it does start building a airbox.

 

[die hard poo]

My mod sled was doing the same thing and it ended up being that my primary spring had sacked out and I was only hitting 7200-7400rpm in the steep and deep. Just like you it would run decent on the way there on the trail. That is where the motor wasn't reallly under a load and I would pull about 7900-8100 rpms. I changed my primary spring to a 120-330 and it absolutely rips. If you get the specs of your spring you could measure the length of it and see if it has shrunk. My spring had shrunk about 1/8th of an inch. Doesn't sound like much but it obvisiously made a huge difference in my sled. I would at least check your primary and see if that is the problem.

 

[Angermangement890]

I would call Carls,I remember 1 guy with a Hot Seat 925, had the same problems you are having, he sent it to Carl's for some revisions to the porting. If I rember right, Hot seat had the exhaust port so high the thing would never hit full RPM out in the thin MTN air.

 

[Old_Focker]

hey thanks a lot on the responses.

I did throw a new primary spring in it this last year and still experienced the same thing.

I think I will call carls and see what they have done. Thanks again for the help. May have to put the old 800 back in her. At least I know how to get that motor running.

 

[Angermangement890]

Careful calling Carls, after talking with Chris you will have a new 860 carb engine on order. Never fails, a simple call to Chris winds up with much less money in my wallet..... funny how that happens.

 

[Old_Focker]

lol he almost got me. I think that 860 might end up in a flat land iqr for around here. I just got off the phone with him and he mentioned that they had issues until they cranked up the timing on the 910 and 925s. I will check my timing this weekend. He was talking 31 degrees at 4k and 19 degrees at 8k. If I can't get it to work I think he will just have to build the next mountain sled. He said he has a shipper that can send sleds back and forth for $400

 

[hudini]

I am running 390's in my 910 and I think the clip on the needle is in the number 2 position...I will have to check the clip though... 10-64's with alomond and 10/64/44team I believe...Make sure you are getting more then enough air to the motor and dial the timing in...Last winter my 910 only pulled 7100 in the IQR chassis but I had a small aluminum air box pulling underhood heat and not much air at all. I changed to the stock airbox etc. for this year a need to ride it to see if it will all work out. The stock airbox requires a ton of work to get it to fit...I had Carl's do it for me.

As far as a tighter pipe working at elevation, it will until you start hitting the hill over and over or are boondocking through the deep causing higher temps. I know this from experience and the only thing that has completely cured the bogg for me was to go with 36mm I.D. pipe from the back of the pipes into a front dump "shot gun" style silencer. No B.S. on this...the only combo that worked on my 910 to get rid of all bogg, huge amounts of air, mod the pipes, and use Struther's tuning.

IMO your fix is not to mod the pipes, but rather go in the direction of timing like others have suggested...It's great to see all of the information from you guys.

 

[Old_Focker]

Thanks again for the feed back

I checked my book and that is basically the same set up I had for the sled out west. 390 mains? I finally got pissed at the pig and kept jetting it down. The thing ran the same with 270 and 390 in it. I have temp guages and could still only pull 1350 on a long pull. I understand pipes getting "pipe temp" high when they are jetted fat. Does the same work with leining the motor down. I literally ran 270's at 10k 20 degrees even though hot seat called for 390s. I run a variflow so I knew I had the option to richen up. I could play with the temps going down the trail with the variflow. The plugs looked a little better

Maybe my timing is way off. I will find out this weekend when I get a light on it. Still rips around here. Except when I lein it way down around here it starts to untread my spark plugs from pre det I believe.

If my timing looks fine I might send it to struthers and have chris hack away. He said the motors are relatively similar and has seen this 925 from hot seat.