New Sled-Engine Questions

[RalleyTuned]

So just picked up a (appears to be) 98 wedgie. It is not running or not running well at least. Was told by the PO that with a bit of starting fluid they got it to start, but it hasn't been ridden in a couple years.

The motor has Union Bay heads on it, and I am not able to find any information on these online. They are blue and say union bay, I know nothing else about them. The engine has a set of twin pipes on it as well. I would like to know some more on the heads or how to identify what heads are on the motor so we can look at the jetting to see if it is setup correctly.

Any help on this? Do these heads raise compression? If so by how much?

 

[sledhed]

I would think the first order of business would be to run a compression check on it to see if it is up to par. If it is excessively low or not even from one cylinder to another then a teardown is in order to see what is going on internally.

If compression is good, disassemble and clean the carbs and make sure the pilot jets and all air passages are clean. Seems like I always had to do it twice to get it clean enough to work right, and all jets etc. had to be removed cleaned and inspected. I would suspect, looking the sled that it has been ridden quite a few miles with the setup that is in it, so the jetting is probably at least close enough to get it started if the fuel system supplies the fuel it needs. Worst case you might need to rejet for an elevation change if ti used to be run higher or lower, but if it is not under load it should start and idle decently anyway.

You can always look on sites like SLPs to find instructions for the 700 big block twin pipe setup, go richer than that, and work your way back down based on plug color and piston wash.

By the way I think that year had altitude compensation which looks like it has been removed, so jet accordingly richer or leaner (I forget which).

Good luck and have fun!

 

[RalleyTuned]

First off, thanks for taking the time to type that all out! haha

We got it up and running yesterday, it just took a few squirts of starter fluid to get it up and running, and after it ran for a few minutes it would start first pull every time. When it was running i turned the choke on and off and there was no difference.

The other thing we found is one of the twin pipes has a huge hole in the expansion chamber. The carbs were really clean looking, but we are pulling them off to clean everything out. The sled was ridden a few times roughly 2 years ago, and the PO had spent the time he had when not deployed to try and get it running better.

First step is replace the pipes and get the stock hood and seat on it. The gas that is in it is 2 years old more than likely and it still ran decently. The idle was pretty high, I would guess around 1500-2000rpm, a very slight blip on the throttle would engage the clutch so we are going to try and get that down a bit as well.

Compression test after it had ran a few time was dead nuts 130 on each side. I have read that other 700's with really high compression heads were in the 150psi range, so 130 should be pretty good? It was exact 130 on each side.

 

[sledhed]

I have been through the old-gas / blocked jet ritual a few times before is all Mostly with motorcycles, but earlier in my riding with sleds as well.

Sounds like it is all good, those are keihin carbs in case I didn't mention it (same carbs on my 99 gen2 600 / 700 twin). I hear you CAN change over to a rack Mikuni set off an 00? or newer but I personally did not think it was ever worth the effort, the keihins run fine when jetted right.

The "choke" is just an enrichment circuit, the cable might be misadjusted or broke or the passages blocked. That might also cause an idle issue (or just the air screws might be too lean or a combination).

Compression sounds good, I would not expect the clutch to begin to engage until at least 4000 RPM, so primary spring might need replacing.

I bet the sled will rip once everything is gone through, the 700 big block was a solid motor.

 

[Ryanlilly]

If you need info on the head call Curt at Fastrax. 253 848 0908

 

[SUBJECT42]

Thank you all for your input (this is my sled). Looks like I have a busy summer either tearing this one apart to fix the little things with the chassis, or locate a chassis sans engine to swap. There are quite a few issues we found not limited to missing rivets and bent parts :/ not ideal but it's a start. Dirtbag skier transportation go!