97 Summit 500 - Icing & Poor start/low speed trail perfomance - Snowmobile Forum: Your #1 Snowmobile Forum

kyholland · 10-27-2009, 11:28 PM

I've got a 1996 built 1997 Summit with HAC that I bought last year. After four trips to dealer and independent mechanic, I would have been better off to buy a new machine... but its mine...

From beginning the machine has run fine when cold for a few minutes... long enough to buy it. But soon after it runs poorly at low 5-6000rmp on trails putting along... seems like I have to give it half throttle to get its attention then back off. Also VERY hard to start warm, even with previous ideas of giving it a little throttle. I either catch it first pull, or I'm pulling. Runs fine half throttle and beyond - except when it hits a hill and and I find plugs are fouled and the engine dies leaving me stranded in deep snow or on the side of the mountain... some tense minutes or longer getting out of a couple stupid sittuations after dying.

Sometimes it seems like carberator icing... gets worse as I'm running in cold weather to the point it is really acting up and won't run at all.. let is sit for a while and it gets better and runs fine at high end. One mechanic put screens over the cowling to cut down on powder.. he also found what he said was water in the bottom of the tank. He also rebuilt carbs and found some problems... but the machine was the same when I went our riding.

Another time found bad coil/wires... but same problems.

Sometimes acts like its guzzling gas.

Last fall REALLY hard to start... seems like it got quickly flooded... or perhaps it was just flooded??? Not looking forward to this weekends first attempt.

Fun to ride mostly - but I don't trust it... suspect that there is an icing problem.. but think that there is really another low end carb problem... suspicious of the HAC system, wonder about primer??, wonder if I should start experimenting with jets. (good compression, but wonder if I should check for lower end leaks...) just going in circles at this point and don't want to go back to mechanics again... seems that testing in a warm shop isn't getting me anyhere.

?? where to start on low end operation??
?? Suggestions on minimizing carb icing??
?? Want to make me a good deal on a clean machine... will run great when you come to try it out!??

Thanks for thoughts and suggestions. Comfortable working on the machine - but its been 30 years since I did much so these new HAC/Carbs are a bit new - even on a 10 year old machine...

Ky
(Wish I had an 600 Etec - but the 500 Summit is mine)

**RJ Gleason** · 10-27-2009, 11:40 PM

Have you checked compression?

kyholland · 10-28-2009, 12:30 AM

Re: Compression... I did when I bought the machine... don't remember exactly - seems like it was 150ish on both cylinders. What's a good compression for dry?wet? cranking compression and I'll go out tomorrow and get current numbers. Machine has about 1700 miles on it. Thx Ky

**RJ Gleason** · 10-28-2009, 08:07 AM

Anything over 125 allowing for altitude.
All plugs out, throttle wide open and 4 to 5 pulls.

**smallengineguy** · 10-28-2009, 01:38 PM

Have you checked to see if the chokes are functioning? They may be stuck in the bores/not closing completely.

kyholland · 10-31-2009, 02:52 PM

Thanks for suggestions. Compression was 135 on both sides. No obvious problem with movement of carb. More thoughts on where to look? Thanks - Ky

**smallengineguy** · 10-31-2009, 03:53 PM

Not the movement of the carbs, the actual choke plungers. Are they closing all the way in the bores?

kyholland · 11-12-2009, 01:47 AM

Humm... we'll I've been looking for "choke plungers" for a couple weeks when I've had a few minutes to dig... does the fact that there are no chokes on this machine that is equipped with a primer make a difference??? I have been learning a lot about the carbs in the process. There is no apparent way to test the HAC system other than replacing it... seems like I need to focus the pilot jet/air screw, cut away (seems unlikely), or needle jet. Any suggestions on how to proceed based on above problems? Previously I'd had problems with the machine not idling so one of the mechanics increased the idle speed to 2500... now I'm wondering if that might be working against me by messing with air flow at starting???? Thanks for suggestions. I'm convinced that this machine should be able to start and run well at lower rpm.... not ready to give up.

**RJ Gleason** · 11-12-2009, 08:07 AM

True, some of those did not have "chokes" (enricher circuit) but only had primers.
The primers would develop a leak over time and needed to be replaced. Particularly the button type, but the plunger type will also do this.

The leaking primer will cause an excessively rich condition at idle that can be masked by raising the idle to near clutch engagement rpm.
I suggest that you look there and possibly replace the primer parts.

burnett01 · 11-12-2009, 07:04 PM

how did the clutches and belt look , I replace my belt and clean my clutches once a year, it will surprise you with the added performance after something little like a cleaning, This might help with trail ridding but not with the hard start, that seems like a fuel issue mabey the floats are hanging up.

kyholland · 11-12-2009, 11:30 PM

Clutch thoroughly checked out. New belt. Will replace primer. Any experience with the HAC - what are symptoms of promblems with that. Manual says no adjust -only replace if suspect but no info on what to suspect! Thanks for thoughts. Ky

lowbudget · 11-13-2009, 12:28 AM

Here is a link for HAC disassembly ski-doo snowmobile forums - DOOTalk.com also do a search for HAC in Summit sub forum of Dootalk.com there is a lot of information there

Ultrafrozen · 11-13-2009, 01:05 AM

Run gas line antifreeze (dry gas?) to prevent any possible icing up issues.