[Rob Aldakimov]

Lissa and I have been having a chronic crank seal problem with our KXs for the last 4 years or so. I am replacing crank seals constanly on them. Everyone that comes out have been rock hard causing the engine to stink trans oil. This season we started out with new motors to eliminate any chance that it was my assembly of the engines that was causing it. On my bike I found a brand new KX250 engine with 0 hours on it from a guy that parts bikes on Ebay. Lissa's 07 KX250 was brand new at the start of the season. Ive switched 2t oils, changed my ratios from 50:1 to 32:1 and 40:1. We used Motul, Golden Spectro and currently use Maxima Super M at 32:1 with a 50/50 mix of Cam 2 and 92/93 octane pump fuel. (Sorry this is long but a little background is needed)
Ive noticed that Lissa' bike started smoking and using up trans oil towards the end of the summer. Mine made it to Stump Jumper when I noticed excessive oil consumption. We started to think it was our riding style, excessive clutching getting the bottom end too hot. Ive never had this problem before on any of my Yamahas and Hondas and also older Kawasakis.
Earlier today I stumbled across a thread on another site about crank seal failure on vintage bikes due to the ethanol that is now present in all pump fuels around my area. They are having issues with seal failures, fiber glass tanks falling apart etc. The fix is a switch to Viton seals. I have heard of cars having multiple issues with their fuel systems due to the ethanol also. I checked my manual and it says not to use any fuel with 10% ethanol. I believe the gas stations are up to 15% now. So what type of fuels are you using and have you had any issues? Im hoping that I dont have to switch to straight race gas!

[Rob Aldakimov]

The bike is sucking trans oil not stinking it. The edit function wont work.

[Brad Rawlins]

My man jeffro brown always runs a 50/50 mix 93 and race gas. And his bike is old.

Food for thought Rob. Btw the e gas is junk.

[Ryan Fitzpatrick]

Rob, have you thought about the startron enzyme treatment? 8 oz bottle treats 48 gallons. Don't know if this will help.

[Scott Lavance]

Just some thoughts....does aviation fuel have ethanol in it? I've been running Sunoco Ultra 93-94 octane with Amsoil Interceptor at 50:1 in the KTM and have had no troubles (knock on wood). Have you guys tried aftermarket seals, or just OEM?

[Rob Aldakimov]

Just OEM. Im calling Cometic tommorow, I heard they use the viton seals. I used to use av gas also, never had any problems. I know Jeffs bike is a 00, thats why I dont understand whats going on! His bike uses the same seals as our 03 and 04s. Lissa pulled her stator cover last night to replace the clutch cable and found a puddle of oil in there. Its coming from the crank seal. I may make the jump to a Gas Gas for the next bike. Wont be for a while though.

[MARC GROSSMAN]

Hey Rob, I use VP 110 leaded with silkolene comp2 at 40:1 on my AF 06' motor. Never had an issue with it or any of my previous 2T bikes running that combo. I run it straight and buy it by the 30 or 50gal drum. Not cheap but effective

[Mike Soudas]

Been seeing more and more ethanol issues from brittle fuel lines, orings in carbs falling apart etc. Seems that constant use motors or motors that are run daily are not as bad, once the fuels sets a few days in the carb/crankcase without heat from running...issues happen..

Startron is awesome in reversing sone effects of ethanol but notmally cold starting and water issues are it's main functions not altering the ethanol...

We run VP C12 or U4.4 90% of the time.. occasional we run a mix of pump premium but drain it or use it all.... KTM use the good seals so the cranks are a bit tolerant.

ALL USA fuel is around 10% with a max of 15%... When the price is up over 2.40 gallon ethanol is cost effective to add... so now we see even more if gas price ever get to the 2.00 / gal we see them throttle it back.

I have friends that are fuel chemists for Phllips/Chevron/Conoco and they work on pump blends to specialty fuels....these guys just say use the proper 2 stroke oils that blend with alcohol based fuels and change hoses/seals as needed and learn how to rejet..then they get to technical.....

Good luck my friend. Tell Lissa be careful with those susies as that fuel can play havoc on those 1970 ish machines.

[timothy souder]

Hard Seals?
Are they discolored in any way near the lip portion that runs on the crank? (Dark or black)
Are they brittle / breakable? Especialy on the insides that face towards con rod?
For twenty or so bucks - You can send in oil samples to specialized vendors and they will tell you if the oil, fuel, coolant or bearings are up to par.....I use this on our GTR and NISMO race engines at EVERY service interval ($20,000 engines). This analysis is very in-depth. They will tell you based on the contaminents in the oil what is happening. It needs to have been ran in the engine fior a normal interval so they can see / test for proper contaminents. Ethanol related issues wil show.

As a side note: AV gas not good for racing engines. Designed for controlled / improved ignition at cold temps and extreme high altitudes. Will cause piston / valve damage on high compression - performance engines at warmer temps and lower altitudes. Can cause a ignitability (is that a word) type problems. Octane RON/AKI is not always the answer............

[Bryan Shaffer]

timothy souder, on 29 December 2010 - 07:16 AM, said:

Hard Seals?
Are they discolored in any way near the lip portion that runs on the crank? (Dark or black)
Are they brittle / breakable? Especialy on the insides that face towards con rod?
For twenty or so bucks - You can send in oil samples to specialized vendors and they will tell you if the oil, fuel, coolant or bearings are up to par.....I use this on our GTR and NISMO race engines at EVERY service interval ($20,000 engines). This analysis is very in-depth. They will tell you based on the contaminents in the oil what is happening. It needs to have been ran in the engine fior a normal interval so they can see / test for proper contaminents. Ethanol related issues wil show.

As a side note: AV gas not good for racing engines. Designed for controlled / improved ignition at cold temps and extreme high altitudes. Will cause piston / valve damage on high compression - performance engines at warmer temps and lower altitudes. Can cause a ignitability (is that a word) type problems. Octane RON/AKI is not always the answer............

Tim
I agree with all except the AV gas statement. Is a stock dirt bike engine considered a racing engine? All I know is that pump gas is a crap shoot, not regulated well enough (Unlike AV gas which is highly regulated), gives all kind of problems when you let it sit in a gas can or tank for even short periods of time, and you cannot trust what you are pumping at the local station (Octane and quality wise). I have been using AV gas(100LL) for 10 years and have everything good and nothing bad to say about it. Oh, and my bike starts right up and runs like a clock after having sat for a couple months of winter storage (I think the shelf life of 100 LL is aroungd 2 years). Also, the prices are much more constant and don't rise quickly and fall slowly......

[mike walters]

Rob, I use something very close to you:

Maxima Super M at 45:1 with a 50/50 mix of Cam 2 [110 leaded] and 92/93 octane pump fuel.

What about radial runnout at the crank?

[Lissa M. Arsenault]

I don't think it's a crank condition issue, having put new OEM crank assemblies into previous engines, having factory assembled new engines, etc. only to have the crank seals dry-up and inhale-oil regardless of model year and design, whether new or rebuilt. What's interesting is my original '03 KX250 and Rob's '03 NEVER had a crank seal issue during those couple of race seasons until '06. Every engine ('03s,'04s & '07) since has been multiple crank seal replacements, like clock work. If I'm recalling this right, that is about when the ethanol started appearing in pump fuels. We have used only OEM seals since I'm skeptical of aftermarket parts (bad experiences with non-OEM parts reliability), but Rob's idea of swapping seals to a material that is supposed to withstand ethanol seems like a fix. He has them on order. I still think, though costly for the amount of gas we go through, that running straight Race Gas may not be a bad idea either at this point.

I didn't think it was the bikes (why else would my '03 have held-up so well during the first couple of seasons?). I know it's not my maintenance schedule. I go over my bike with a fine-tooth comb and handle all of the prep and rebuilds personally (anything out-of-order on my bikes eats at me, so they gotta be perfect). Someone said heat could be eating the seals. I was having a hard-time believing that I'm any harder on a bike then a pro is and their bikes stay together! I know I'm a knucklehead, but I ain't dishing out Pro rider abuse either! All the Team Green off-road guys 250's stayed together, and they weren't getting nearly the amount of attention the factory MX guys bikes did. Besides, my bike didn't loose a drop of coolant the ENTIRE season, so it has to be something else. It's gotta be the fuel and the seal material.

Case in-point, previous seasons ('06 on up) we would use much lower amounts of race gas, usually 1/3 up to 1/4 (1 gal Race to 4 gal 93 pump, etc.). Crank seals would quickly harden (twice a season or worse) at that ratio. We played with oil ratios, talked to Kawi's tech, etc. When I put my '07 into use, we had to use at least 50/50 race fuel, since it's prone to pinging badly at any lesser ratio otherwise (even with fatter jetting). So this past season, we started with two factory fresh bikes, 50/50 mix and managed a whole season before wiping the seals. That tells me it's gotta be the ethanol in the pump gas and the OEM seals material. I'm thinking other folks may not have this problem on bikes equipped with standard seals because they probably aren't putting tons of mileage on their bikes during the course of a year (my bikes get well over 2,000+ per year). Alcohol evaporates quickly, so my thinking would be that a bike that's getting run at least once a week for several hours at a time is having constant ethanol exposure to it's cranks seals where a bike that sits most of the time would have any ethanol left in the crank evaporate shortly after being parked. Now the carbs, fuel lines, tanks, etc. are a different story.

Sorry this is sooooooo long. I just wanted to explain. I was curious too as to what everyone else used for fuel (race, pump, av or pump) since the further we look into this, it seems ethanol is more of a issue then "made-light of". I'm just angry I blew so much time chasing our tails the past few years when it was the pump gas all along.

[Lissa M. Arsenault]

FYI other Jap 2str riders, I found a vague list on a website that states to not use "E5" or "E10" (what ALL pump gas is in NJ) in any Honda, Suzuki, Yamaha or Kawasaki motorcycles (makes sense, Japan doesn't use any ethanol). It didn't list any Euro manufactures except BMW which it said is fine with E10 which would lead me to believe that the other Euro brand bikes would be ok too (Europe uses a lot of ethanol as well). It also said HD and Buells were ok with E10.

[Mike Soudas]

Since I am a fuel junkie amoung other things urgh!!! not schooled with a degree but well versed...

Tim.. you are correct, plus AV gas 100LL octane is not rated the same as pump fuel or race gas, it equals about 96 on the gas pump scale..
Also testing the 2stroke oil residue in a crank for contaminates is almost impossible.. it will show alot of unburned hydrocarbons and such since it is near impossible to extract the oil left from a combustion cycle at the exact moment where it is just an oil and not part of the combustion process......


Bryan, you are a gambling man shooting craps with Av Gas LOL...
AvGas has other additives that are not the best for a high reving dirt bike, it does help with the octane needs.. It is slightly more consistant. It distillation curve is better sutied for a bracket racer than a dirt bike, throttle respnse can be so so... I have seen a many of smaller displacement Hi Revers come undone on Avgas as it provides little piston cooling under stress..
But we are talking seals and such, so no real debate, I have lots of locals run Avgas and it helps with jetting on occasion and they all seem happy, so it is fine for the masses not me except for a splash in my 68 torino GT...

Lissa

The Ethanol in question evaporates completely or boils att approx 78 degrees "C".. approx 170 F .. but it starts to evaporate quickly like you describe and can eat away or harden some seal materails...
I can atest to seals and rubber parts in older cars like my torino and other I have getting damaged carb parts.. I had to rebuilt with alot of MCMaster/Karr oirings and such since you can only get old NOS rebuild kits or univeral chinese junk... In one of the other motor I have it have never seen Ethanol pump gas and uses a steady diet of VP110 or RED and it is very happy since 1967....
I am curious on these seals and such, I have some OEM KAwi, SUZI and HONDA crank seasl on the shelf, time to experiment in some glass jars....

[Bryan Shaffer]

Mike Soudas, on 29 December 2010 - 07:17 PM, said:

Since I am a fuel junkie amoung other things urgh!!! not schooled with a degree but well versed...

Tim.. you are correct, plus AV gas 100LL octane is not rated the same as pump fuel or race gas, it equals about 96 on the gas pump scale..
Also testing the 2stroke oil residue in a crank for contaminates is almost impossible.. it will show alot of unburned hydrocarbons and such since it is near impossible to extract the oil left from a combustion cycle at the exact moment where it is just an oil and not part of the combustion process......


Bryan, you are a gambling man shooting craps with Av Gas LOL...
AvGas has other additives that are not the best for a high reving dirt bike, it does help with the octane needs.. It is slightly more consistant. It distillation curve is better sutied for a bracket racer than a dirt bike, throttle respnse can be so so... I have seen a many of smaller displacement Hi Revers come undone on Avgas as it provides little piston cooling under stress..
But we are talking seals and such, so no real debate, I have lots of locals run Avgas and it helps with jetting on occasion and they all seem happy, so it is fine for the masses not me except for a splash in my 68 torino GT...

Lissa

The Ethanol in question evaporates completely or boils att approx 78 degrees "C".. approx 170 F .. but it starts to evaporate quickly like you describe and can eat away or harden some seal materails...
I can atest to seals and rubber parts in older cars like my torino and other I have getting damaged carb parts.. I had to rebuilt with alot of MCMaster/Karr oirings and such since you can only get old NOS rebuild kits or univeral chinese junk... In one of the other motor I have it have never seen Ethanol pump gas and uses a steady diet of VP110 or RED and it is very happy since 1967....
I am curious on these seals and such, I have some OEM KAwi, SUZI and HONDA crank seasl on the shelf, time to experiment in some glass jars....

Mike
Not to get into a pi**ing match here, but I have heard the same info from other people and funny enough everyone says "exactly" the same thing word for word (Almost like the info is being passed around from the same rumor source), and I have not experienced any of the above issues you describe. As the matter of fact my piston looked great the past two ring replacements (Before I used AV gas I was replacing the piston and the rings yearly). Again, I can only go by what I see and experience. I would have to say though that having raced a couple full seasons on this stuff with good results, it sure seems as if it is "race proven" and reliable too.