Horstman DXL Wet Clutch Issues. Need Guidance!

rowanmagnuson

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Hey there!
Recently purchased a go-kart... and I don't have much experience. It has a kt100 engine and a Horstman DXL Wet Clutch. I have completely rebuilt the carb and it runs great. I was finally gonna take it for a spin and........ nothing. It just revs and refuses to move. So I start investigating the clutch. I ordered new springs but that has not seemed to help. I was curious if you might be able to provide some guidance, I would really appreciate it. I can provide more details if anyone thinks they can help.
Thank you!
 

JimD

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First make sure it has the woodruff key on the taper (half moon key). Depending on how new the engine is the key may be metric. The older engines it was 1/8". Are you using 219 or #35 chain?? Terry Ives in CA just had some new drum and sprockets made up for those clutches in the #35 chain (9 tooth and 10 tooth). Horstman had it own oil it recommend for the clutch. They are normally set for a 9,000 engagement so you have to put the pedal to the floor. Don't baby it and get it locked up asap. Terry would also have the disk and plates for the clutch if yours doesn't have the lining on them any longer.
 

rowanmagnuson

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thanks for your response Jim, I appreciate it.
It should have half moon key as the inner part with all the triangles is connected to the engine and the outer drum part is connected to the chain like it is supposed too. We are using a #35 chain. Unfortunately, we have not been able to get any of the original Horstman oil, instead using a Synthetic Tranmission Oil we got at the local auto shop. Could that cause issues other than just wearing down the disks faster?
I believe that we have not even gotten close to 9,000 rpm, so you might have just solved our problem. I will try flooring from the start later today and see what happens.
what do you mean by thing lining on the disk and plates? I measured the disks, they are at roughly 0.08” thickness which is almost the minimum that they should be at.

We tried a few things that I didn’t list in the original post. At the beginning, the clutch was always engaging, even after adding oil. We could push the kart around without it engaging, but when we actually started the engine it would engage at idle speed. If we try to stop the wheels with our foot or the brakes, it kills the engine. The engine idles around 3000 rpm.
The documentation online really stressed the importance of the air gap. Unfortunately, it seems like we cannot measure the air gap without some special tool to remove the entire clutch (right?) I already purchased some feeler gauges in case there is a way to measure the air gap.
The clutch has a spacer in it, the one with little teeth and holes. The clutch still constantly engages with this spacer in. We start the engine with the wheels up off the ground, and they spin. If we try to stop the wheels with our foot or the brakes, it kills the engine. Could this be because the air gap is wrong? We tried this with the springs tighten to their max (within the ranges listed in the documentation) and loosened to the max, still engages constantly. We had the perhaps genius, perhaps horrible idea of taking tinfoil, cutting it to the right shape, and using it to thicken this spacer. We added about 6 layers of very thin tinfoil. When we do this, the clutch does not constantly engage. However, it seems to not be engaging, although this could be because we are not giving it enough throttle. Could the issue be that we need a different sized spacer to get the air gap right? What is the purpose of the spacer, and how does it affect the engagement?
 

rowanmagnuson

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Here is a photo of the engine and clutch.
 

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JimD

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Several things you can check out yourself is to make sure the floater disk are not warped. They would be the spacers between the plates with the lining material on them. Just take them out and put them on a plate of glass and make sure there is no room for a feeler gage to slide under, flip over and double check both sides. It is duplication but you just might notice a gap on one side and not on the other. These have to be perfectly FLAT. Terry Ives (tii@surewest.net ) would be the person who could tell you just how to set them up for the Yamaha.. E-mail him and ask him for the education. He was one of the best drivers that Horstman ever had and he knows that clutch well.
 
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