neonsurge Posted August 30, 2004 Report Share Posted August 30, 2004 I've just been reading r2w's site where he describes how he discovered that the cause of his Gasser Pro running hot was a pinched outer head gasket (http://www.r2wtrials.com/html_files/tech.html). I've noticed that my Rev-3 is exhibiting similar symptoms (fan cutting in after only a couple of minutes' riding) as well as an accompanying pinging that I'm STILL trying to eliminate. Being pretty mechanically naive, I'm assuming that the Beta cooling system is similar to that on the GasGas and that a pinched or otherwise leaky head gasket is a possible cause of the hot running (and possibly the pinging)... worth looking at the head gasket(s)? Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted August 30, 2004 Report Share Posted August 30, 2004 Probably the last thing you should check. I'd first look at the plug and see if the color is too light (lean). Clean the carb. Check for intake leaks between carb and engine. Have you ever altered the timing or loosened the flywheel for any reason? If so, it could have shifted and put your timing out of the acceptable range. Has the bike ever run satisfactorily since you've owned it? Pulling the head, though, is very easy. If you're really interested in checking/eliminating the possibility, you certainly could...but it's a longshot. Also...if you are "mechanically naive" make sure you have a torque wrench and a book (or knowledgeable person) to help you. Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted August 30, 2004 Report Share Posted August 30, 2004 Clean the air filter, too! Quote Link to comment Share on other sites More sharing options...
neonsurge Posted August 30, 2004 Author Report Share Posted August 30, 2004 (edited) Thanks Charlie. I've had the pinging problem since I've had the bike (as a quick trawl through the forums will show!) It's not severe but gets worse as the engine gets hot. To be honest, I've only recently noticed the fan coming on very quickly in the past month or so although it's so quiet I might just not have noticed previously. I've replaced the air filter, cleaned the carb numerous times (I do this every couple of rides as a matter of course) and checked the timing - all to no avail, hence my wonderings about the head gasket in the light of Heath's experiences with his GasGas. I've been thinking about maybe going up a size on the pilot jet as clarkp previously recommended but since I know lots of people with similar vintage Betas (2003 270), none of whom are experiencing the same problem (although a *slight* knock seems to be normal), I've resisted this route until now because it evidently shouldn't be necessary and may simply "mask" the real cause. HOWEVER, I've just downloaded the Mikuni VM series tuning manual and the exploded diagram shows a gasket between the float bowl and the carb body, something that's definitely missing from my bike and has been since I bought it. The manual isn't specific to the model 26 as found on the Beta, but I assume that it should be there? Could this be the cause of my problems? As always, all advice gratefully received! Edited August 30, 2004 by neonsurge Quote Link to comment Share on other sites More sharing options...
jaylael Posted August 31, 2004 Report Share Posted August 31, 2004 Neonsurge: Head gasket failure should be pretty easy to diagnose. Here's how. When you start the engine up cold. Run it for about one minute, shut it down, then quickly remove the radiator cap, while intently listening for a quick rush of escaping air. This is sure proof of head gasket leak. If your fan comes on qickly, it couldbe caused by low coolant level, incorrect fan thermostat (turn on threshold temp.) or the fan impeller is not being driven or has broken. (This one causes bad overheating though.) As far as the pinging goes, don't hesitate to go for a larger pilot jet. On my Montesa I went from a #30 stock pilot jet to a #38 with incredible improvement in general running and starting, plus no pinging on unleaded premium fuel at 40:1 with silkoline comp 2. I run this in all my bikes from vintage Maico to the Hodakas, and Suzuki RM 400 with excellent results. The Montesa could do with 80:1 or so but it would end up in the other bikes and for them it's just not enough oil to prevent con rod failure or seizures. Jay Quote Link to comment Share on other sites More sharing options...
neonsurge Posted September 2, 2004 Author Report Share Posted September 2, 2004 OK, one quick call to the nice people at Allen's Performance later and I've installed a 37.5 pilot (I bought every size from 30-40 and 37.5 seemed a reasonable starting point!). It started from cold with the lightest prod and just running it on the driveway it sounds a lot more... "open". Nowhere near as much smoke from the exhaust as usual although I don't see how this and the change of pilot jet can be related Just coincidence I guess. Anyway, we'll see how it goes at the weekend - 2 trials to ride! Thanks for everyone's help! Quote Link to comment Share on other sites More sharing options...
neonsurge Posted September 4, 2004 Author Report Share Posted September 4, 2004 Thought I'd close the loop on this one. 37.5 pilot has cured it. Bike runs beautifully with not a hint of pinging. Big thanks to charlie and clarkp for all of their suggestions. Quote Link to comment Share on other sites More sharing options...
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