I'm wondering if anyone has some good info in regards to coating a 2 stroke pipe with Jet Hot or HPC. I've done race car headers and exhaust but don't know that I've seen it done on a dirt bike. I'd like to have the low maintenance that it offers but am wondering if it would affect performance in a negative way. One of the main reasons we do it on race cars is to keep the heat in to maintain the velocity to scavenge the cylinder well. Will this scavenge a 2 stroke cylinder too much and cause a loss in performance? I would suspect that different wall thickness pipes would also react similarly although to a lesser extent. Thanks for any insight!
Ceramic Pipe Coating
- Thread starter gn83tm
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I had looked at those threads but wondered if anyone had any solid info in regards to coating a 2 stroke pipe. If I understand RR correctly, he feels that there would be little performance gain. That's ok since I am more after the looks and low maintenance as long as I'm not giving up any performance. Actually on the job I'm working on it may not matter too much since I built the pipe from a box of parts from DynoPort and I'm not sure what the performance characteristics are going to be anyway. Its a hybrid bike with a KDX motor in a 2003 KX125 chassis.
B
biglou
The Big Gun pipe I had on my 426 was ceramic coated and it held its look well. Never rusted, etc. I can't imagine any performance loss from the coating. It is my understanding that keeping heat in the pipe with wrap or coating increases performance a bit?
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Keeping the heat in the pipe will help to increase the velocity of the exhaust gases which is what helps to scavenge the cylinder. Whether or not the coating will increase the velocity enough to overscavenge is what I'm wondering. Maybe you can't overscavenge in a situation like this. I know that in some race car applications you can actually start to draw out some of the intake charge since the intake valve starts to open before the exhaust valve is closed. Some of this is good, too much is not.
2strok4fun
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- Apr 6, 2002
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Hotter gas in a 4s pipe has greater velocity, like allready stated, but in a 2s pipe, it is not so much the gas velocity (I dont know how much it will play, but Id say not much) but the pulse wave speed. Since speed of sound is affected by temp, a hotter pipe will reflect the the - wave and the + wave back sooner, effectively shortening the pipe, making it more of a rev pipe. The amount of rpm the torque moves higher in the rpm, I would guess would not be that great, but could possibly cause a small but noticable loss of low rpm torque.
All in all I would guess that the diff will be small and could maybe be overcome with a torqe ring if available, if the difference is even noticable. Go for the cosmetics.
All in all I would guess that the diff will be small and could maybe be overcome with a torqe ring if available, if the difference is even noticable. Go for the cosmetics.
DEANSFASTWAY
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- May 16, 2002
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Ive done a fair bit of the Jet Hot on older vintage bikes and on Sleds I recently sent a couple pipes to an anodizer in Philly where we had them nickle plated it was pretty cheap.
Lorin
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- Jun 25, 1999
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Ive coated my two stroke and 4 stroke pipes with the ceramic coating and am happy with the results. As to any performance gains, the two stroke didnt seem to be affected like the 4 stroke was. I didnt really notice any difference with the stock, two-stroke pipe, but the xr 200 pipe seemed to run marginally better (seat of the pants). As to durability, I am extremely pleased with the results. The only bad side is that if you dent your pipe, the heat resilience of the ceramic coating makes it hard to heat \ freeze the pipe to take the dents out. I have a pipe guard, so havent had this problem.
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Thanks to all for the input. Since the season is here and I'm itching to ride, I just picked up a can of VHT clear header paint and sprayed the pipe last night. It's baking in the oven (in the shop - not the kitchen) as I type this.
I did call the guy that does my race car ceramic coating (Moore Power coatings, Waverly, NE) and he said he knows of no issues with ceramic coating the 2 stroke pipes. He said it usually runs about $75 to do a pipe. I will probably have him do it during the off-season provided I don't have any bad incidents with rocks between now and then if you know what I mean.
I did call the guy that does my race car ceramic coating (Moore Power coatings, Waverly, NE) and he said he knows of no issues with ceramic coating the 2 stroke pipes. He said it usually runs about $75 to do a pipe. I will probably have him do it during the off-season provided I don't have any bad incidents with rocks between now and then if you know what I mean.
LA Sledboy
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- May 5, 2004
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Pipe Coating
Like someone already stated in the two stroke pipe runs off of harmonics or sound waves. If nothing else what the heat wrap or coating should do would be to allow you to have a more consistant performance from your pipe. If it can maintain a certain temperature by not losing heat as easily you should get more consistent results. I have found that in sledding where you are working with tuning clutches that can drive you crazy this is a help. Also though if it allows your pipe to operate at a temperature that it wasnt able to before you may see power gains you didnt notice before. I found this on my rotax 800. I tried everything under the sun to get my new single to perform and nothing would show me any gains over stock. I wrapped the pipe and BOOM when it was hot I was seeing 300 more rpm than I ever saw before. Clutched for it and in real world testing I improved.
One more thing though that worries me about your pipe on a bike. On a sled you have a y-pipe for multiple cylinders that runs to the pipe. Some people argue not to coat the y and allow some heat loss before the pipe because too much heat could cause you to burn down. I know you can have twins or triple pipes where you wouldnt have a y-pipe and that is what a bike pipe is like. I see lots of these coated without problems so that may be a myth.
Does anybody in the dirtbike world run egts.
Like someone already stated in the two stroke pipe runs off of harmonics or sound waves. If nothing else what the heat wrap or coating should do would be to allow you to have a more consistant performance from your pipe. If it can maintain a certain temperature by not losing heat as easily you should get more consistent results. I have found that in sledding where you are working with tuning clutches that can drive you crazy this is a help. Also though if it allows your pipe to operate at a temperature that it wasnt able to before you may see power gains you didnt notice before. I found this on my rotax 800. I tried everything under the sun to get my new single to perform and nothing would show me any gains over stock. I wrapped the pipe and BOOM when it was hot I was seeing 300 more rpm than I ever saw before. Clutched for it and in real world testing I improved.
One more thing though that worries me about your pipe on a bike. On a sled you have a y-pipe for multiple cylinders that runs to the pipe. Some people argue not to coat the y and allow some heat loss before the pipe because too much heat could cause you to burn down. I know you can have twins or triple pipes where you wouldnt have a y-pipe and that is what a bike pipe is like. I see lots of these coated without problems so that may be a myth.
Does anybody in the dirtbike world run egts.
Coating
Do not coat the inside of the pipe unless you want to deal with jetting for it and it will lower RPMs.
I did it on an atv and a sled,it worked well but I did the inside of the sled pipe and it lowered the RPMs 500 rpm and ti leaned it out a bunch I burned the motor down on the test.
I don't want anyone to have to learn from their oun mistake on this one.
Do not coat the inside of the pipe unless you want to deal with jetting for it and it will lower RPMs.
I did it on an atv and a sled,it worked well but I did the inside of the sled pipe and it lowered the RPMs 500 rpm and ti leaned it out a bunch I burned the motor down on the test.
I don't want anyone to have to learn from their oun mistake on this one.
