exhaust smoke & oil

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#1
I have a 1991 kdx 250 (just bought) even when hot the bike blows smoke (quite a bit when cold), oil lightly spits from the exhaust and leaks from around the connection of the exhaust to the barrel. The bike appears to have plenty of commpression and is quite crisp in the powerband. Is this normal ?.I am running castrol TTS fully synthetic oil at 32:1 I have noticed articles in this forum about oils and how the use of some oils needing power valves to be cleaned. Would this cause exhaust smoke if so whats involved in cleaning the power valves. The exhaust is a pro circuit.
 

MikeT

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#2
Fully synthetic oils need VERY high temps to burn completely but they protect well. Petrolieum oils burn at lower temps but don't protect as well. What to do??

Try Maxima SuperM at 32:1. It is a semi synthetic oil that burns better than a fully synthetic but protects as well. It has been working for me for at least 2 years now.
 

smb_racing

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#3
I'll have to disagree, the part synthetic Klotz I used to run had a much higher flash point than the full synthetic Mobil MX2T I run now. Sounds like you're just jetted a bit too rich. Also try repacking your silencer, it has probably become oil saturated.
 

MikeT

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#4
Originally posted by smb_racing
I'll have to disagree, the part synthetic Klotz I used to run had a much higher flash point than the full synthetic Mobil MX2T I run now. Sounds like you're just jetted a bit too rich. Also try repacking your silencer, it has probably become oil saturated.
I have to disagree with you smb. The information I stated above came straight from Maxima thamselves. Plus the results they claimed would happen, no spooge because of the semisynthetic composition on the SuperM oil, did happen. I did not change anything but oil type from 927 (fully synthetic) to SuperM (part synthetic) and now have no spooge. The proof is in the pudding my friend.

Also, as smb said the silencer is probably full of oil, repack it.
 

smb_racing

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#5
The technical info from Klotz's Website claims a flashpoint of 460°F for the SuperTechniplate I used to run. The MSDS for Mobil MX2T shows the flashpoint to be around 190°F which is much lower than the Klotz. The MX2T is full synthetic whereas the Klotz is a blend containing 20% castor and the rest a synthetic base. Is this the case for all oils? Probably not, but in this comparison the synthetic would burn sooner.
 

MikeT

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#6
Interesting. I know the SuperM works, so now I'm interested in the flash point. Whatever it is it's working. I'll see if I can find out some more info. Either way Glenn might want to try SuperM
 

MikeT

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#8
Ya, thats it. The 927 has a flash point of 420F and the SuperM is 280F which is low enough to not spooge in my bike. That's why I recommend it.
 
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#9
Not to dispute what has already been said about oils, but my experience with my KDX 250 gives me a little insight into Glenbear's problem. The KDX 250, if it still has the stock jetting, is terribly rich, causing the familiar spooge and mosquito fogging. glenbear, I don't know what mods, if any, your bike has, but you can reduce the spooge considerably, and unlock a lot of hidden performance, if you will take the time to jet that bike correctly. The best thing you can do is to go to the next leaner slide, or, if you are mechanically capable, modify the existing slide. All of the carb circuits in that bike are way too rich, so take the time to jet it. I use Yamalube 2R at 32:1, and have almost no spooge from my bike.
 

125 rider

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#10
I've gotten the best results with Maxim SuperM and Yamalube. Bel-Ray and Golden Spectro worked poorly in my bike.