Hey All,


Just wanted to start by saying thanks to all the pros that make this forum great. I've already learned so much in just a couple of days of reading!


I have a 96 sportsman that has sat for a couple of years. As a learning project I wanted get it running again. So to start I rebuilt the carb, new battery, clean gas, oil change etc.


Once this was done I could only cold start it using starting fluid. Once running for a couple minutes it will idle perfectly and can be started again on the first push of the electric starter. Obviously this is not ideal and actually is the main reason it sat for so long because it wouldn't reliably start prior to shelving it.


However, this time I am determined to find a fix. After reading a ton of different threads here, it looked like the next step was to check the valve spacing and exhaust lobe on the cam. Well, the good news is the top engine was very clean and I found out that it had been rebuild in the last few years. The cam lobes seem good as I'm getting good movement on both the intake and exhaust valves.


In checking the valve spacing I found the intake valves were much too tight and the exhaust valves were too loose. I thought perfect, this has to be the issue! I changed all 4 valves back to the .006 factory settings and put it back together. Unfortunately it won't start at all now!


So my guess is the new cam calls for different spacing than the old factory cam but I don't know what that spacing should be. So I'll be putting the spacing back to the measurements it was before I adjusted it and be bake to where I started.


So my question is, am I missing anything else that could cause this cold start issue other than the valve spacing?


One other issue that I'm wonder if it's related is my pull start is extremely tight and will actually catch where it cant even be moved with a clean pull. To check I pulled the pull start off and found the pull start itself is in great condition and pulls freely. The flywheel seems like it's in good condition other than being so tight.


Sorry for the long first post here are the cliff notes


TLDR - Cold start issue. Changed valve spacing to factory and won't start at all now.


If anyone has any thoughts I would appreciate it!


Thanks,
Craig

 

Valve clearance specs didn't change.. .006 intake and exhaust. Only being able to start by starting fluid either means you're not get fuel to the carb(fuel pump) or jets are still blocked up. Pull the fuel line from the carb and crank the engine over. Should have a steady or pulsing stream of fuel. If the pump is ok,install a good carb kit.. Don't just try to clean a carb that's been sitting for years. Here's a good Shindy kit that's made in Japan,same as your Mikuni carb. New Shindy Carburetor Carb Rebuild Repair Kit for Polaris 425 Magnum 1995 98 | eBay On the recoil starter,remove the 10 mm bolts and grease the plate. Check that the wishbone spring is in place and that the ratchet is kicking out ok. Reinstall the plate and bolt(use blue locktite on the bolt) tighten until the recoil is hard to operate,back off the bolt until it's easier. The locktite will harden and keep the bolt from backing off from the plate.

 

Thank ya sir! I'll check the fuel pump tonight but wouldn't that cause it not to idle as well if no fuel is getting to the carb? Or can it idle on a trickle where I might need a blast of fuel to start?


I did put a full new kit on the carb all new jets and o rings and when it's warm it runs great. Its just that initial start after it's been sitting for 30 minutes or so.

Thanks again!
Craig

 

Is the choke working?

 

Yeah the choke "seems" to work fine. When I had the carb off I cleaned and made sure the cable at least operated properly. Now if there is an adjustment I should have done to test it I didn't do that. I'll look in the service manual for choke adjustment tonight as well.

Thanks!
Craig

 

Look in your manual at the fuel section.. Will give you some good info on the carb itself along with float setting,etc. Here's another fuel section that shows your Bst34 carb along with several others.https://www.google.com/url?sa=t&rct=...U2gGlaHJWSIlbA

 

Just wanted to give a quick update since you both were nice enough to help. So kind of embarrassed about this but went back last night to check the valves again and make sure I didn't miss anything. Well I tore everything back apart and the valves looked perfect, cam was good etc. Unfortunately what I found was, when I was putting everything back together the night before my spark plug socket bushing pulled out and stayed on the spark plug thus not allowing the wire to attach to the spark plug. Obviously this is why it wouldn't start at all after the initial valve adjustment.


Now with everything in place it seems that the valve adjustment did the trick! It started up perfectly last night as well as this morning after sitting all night. One last test will be once it gets out of the 60's here and see how it starts in the 20's 30's that it normally is this time of year.


Thanks again for all the help I really appreciate it!


Thanks,
Craig

 

Simple things over looked cause the most problems at times. Glad you found it..

 

I never would have looked for that.