Tillotson HR Carburetor Problem - Snowmobile Forum: Your #1 Snowmobile Forum

geminimissions · 08-16-2012, 06:21 PM

I've been recently having a hard time getting a Rotax 299cc running properly, or rather to at all. The main problem is the Tillotson HR15A on it doesn't seem to want to pump any fuel. I have tried priming the lines and spraying mixed gas into the intake but it only will fire a few times and not suck anything. The fuel filter is clean, pickup line in the tank was replaced and is venting properly, the impulse line is not blocked, check valve is not seized, and it has great spark and compression. I read that it could possibly be crank seals? Either that or the carburetor isn't put back together correctly/missing parts. I've tried various combinations with the diaphragms to no avail. I've attached pictures on how I assembled it step by step starting with the bottom piece. Does everything look as it should?

Thanks in advance.

**smallengineguy** · 08-17-2012, 03:52 AM

Try this:
Tillotson HR

geminimissions · 08-18-2012, 12:38 AM

Thanks for the reply. It appears that I'm missing a few gaskets/diaphragms and will just order a replacement kit. I also have one more question; can I swap it's bogie suspension with a slide one? All of the bogies are badly cracked and it would cost a lot to replace all of the wheels. The guy I got it from threw in an extra slide suspension in decent shape other than the fact it needs new slides. The mounting holes are the same distance apart on the chassis as they are on the suspension. Would it bolt right in?

Mpolly500 · 08-18-2012, 05:54 AM

I had a Sachs motor that used the HR carb. Mine only had the pieces yours does. I think some did and some didn't. I had nothing but trouble with mine. Would run great then not start. I ended up swapping the HR for a mikuni. After that I never had a problem. Those diaphram carbs have alway been a pain.

**smallengineguy** · 08-19-2012, 08:34 PM

It may bolt right in, but you need to make sure the geometry is correct. What sled did it come out of?

geminimissions · 08-20-2012, 02:25 PM

I'm not sure what sled it came from, but the guy I got it from said it should bolt right in. I think I'll try it because slides are much cheaper to replace than bogies.

Thanks again,
Andy

geminimissions · 08-23-2012, 07:00 PM

I replaced all of the gaskets and diaphragms in the carburetor along with adding one that was missing. I also put a in-line primer on the fuel line. It's 100% clean and the needle is not sticking. I can get it running for a few seconds on spray but can't keep it going on it. It seems like it tries to run at full throttle induced by the spray but won't keep going. Probably isn't relevant but the smoke is white and doesn't smell like it should which is probably because it hasn't ran in forever. Either way, I'm getting pretty frustrated with it and don't know what else to do. Any ideas? I'm starting to consider swapping it out with a mikuni.

Mpolly500 · 08-24-2012, 05:32 AM

On the HR in the carb body there are two small plugs by the inlet needle. They look like small shinny things. A good rebuild kit will come with new ones and directions in how to change them. Under them Is kinda a jet passage way that can build up with crud. The only way to clean is to remove those plugs. You use a small 1/8" drill an drill a hole in the plug. Be very careful it's thin. Take your time. Once the hole is drilled use a small punch or pick to pop out the old plug. Then you have access to clean. A good soak once both plugs are out will help alot. The swap mikuni was the best thing I did for that motor. I've had the HR carb on a few things an never had much luck with them

**RJ Gleason** · 08-24-2012, 05:57 AM

That is the Welch plug, the standard rebuild kit does not usually include those. You have to buy the complete kit.

Mpolly500 · 08-24-2012, 08:04 AM

I knew it had a name couldn't remember. I bought a nice kit off eBay only like $15 an came with everything even nice detailed instructions.

geminimissions · 08-24-2012, 12:21 PM

Thanks for the replies, guys. I have spare welch plugs that I ordered as well as the kit. The reason I didn't mention anything is because I already removed them and replaced them with some from a small engine shop. I'll take them out again and probably run some wire through the holes, soak it, and hit it with compressed air. Hopefully it will be the last time I have to take the carb off the motor.

fmalott · 09-13-2012, 12:40 PM

Quote:

Originally Posted by geminimissions

Thanks for the replies, guys. I have spare welch plugs that I ordered as well as the kit. The reason I didn't mention anything is because I already removed them and replaced them with some from a small engine shop. I'll take them out again and probably run some wire through the holes, soak it, and hit it with compressed air. Hopefully it will be the last time I have to take the carb off the motor.

I just kinda thinking make sure the carb body is not cracked somewhere and your sucking in to much air and when i rebuild a carb tillotson or mikuni even if i think the needle and seat are not sticking i still do a test clean out all gas from carb then put a fuel line on the inlet hold the carb upright then blow into the carb if air passes threw then the needle is not sticking then repeat with the carb upside down if air passes threw then the needle and seat are no good then slowly turn the carb right side up again and blow in the carb to see if air passes threw if it doesn't or it doesn't pass threw freely then the needle and seat is stuck. it's a very simple test and it save you from much trouble later down the road