dan williams

Heh heh like I'm ever over 3/4 throttle.

Website looks legit but I'm always suspicious of such obvious mistakes.

We're just scared of your avatar. What year bikes? Any exhaust or airbox modifications? Mikuni or Keihin. You see it's not a cookbook question. There is no "correct jet" There's only the correct jets for your bike, altitude, air density, temperature, riding style. That's one reason people are a little leery of wading in with a set of numbers. Carb tuning information is readily available on the web. Google for the Mikuni tuning guide I think from SUDCO. That should give a rough estimate of how many jet sizes you'll need to go down for altitude but you really need to spend the time to do the testing with the bike and a set of jets if you want it done properly. I usually carry a couple of sizes plus and minus of both pilot and mains when tuning. Yes it's a pain but it's so worth it. Having said that usually around here people go down one size on the pilot to a 27.5 and one size on the main to a 130 for the 270 with a Mikuni but we're at sea level.

I got to compare a stock '08 270 to mine yesterday. Interesting to see the differences the clutch mods, Akropovic pipe and VForce reeds make when you can hop off one bike onto the other. For one thing my clutch is very progressive and the pull is significantly less. My buddy's clutch is like a light switch and I don't think I could ride a whole event pulling in that clutch. The engine feels very different on the bottom. Mine is very smooth, almost soft from idle to about 1/4 throttle feeling like there's more flywheel then there is. His snaps right off idle and quite frankly almost got away from me a couple of times. Above 1/4 throttle the power curves converge so above 1/2 throttle they feel virtually identical. At least that's how they feel for the very short amount of time I can spend in that part of the power curve without kissing a tree. Also worth noting I had to change my jetting for the VForce reed his seemed right on stock. It'll be interesting to ride his bike after he puts the heavy spring on the rear.

Finished on one peg? Yikes. That takes guts.

I was thinking about a plastic float bowl but then I remembered my friend who broke his cylinder head in a crash and thought better of it. A broken float bowl could be very dangerous. I still give him a hard time about it. How do you break a cylinder head? He literally caved it in on an easy flat rock that everybody just rolled up on the first loop. After he doused the rock with antifreeze it was impossible to ride. Of course nobody knew that until they came around again and found out too late that it had become slippery as ice. Almost put me on my head.

My first answer would be, More trouble then it's worth. That's a pretty sad looking machine.

I'd be inclined to go for the basics first, make sure throttle cable didn't get yanked out of fittings, kill switch jammed and stuck, flooded engine causing wet spark plug. Past that look for the basic things it needs to run. Fuel, air, compression, spark. My money's on the wet plug which has probably dried out by this point and the thing will just run. Always have a spare plug in the tool box. Let me know if I win .

If it's coming from the overflow tube at the bottom of the float bowl then it is usually one of several things. As already pointed out, a piece of dirt holding the needle valve open. Disassemble and clean compressed air works but I'll throw a Q-tip up there as well being careful to not let any of the fibers escape and stick in the valve. There have been a few reports of floats binding on the float bowl gasket and in very rare cases a leaky float filling with fuel. If it's coming from the vent tubes that come from the brass fittings near the top of the carb that's a different matter and is simply the tubes acting as siphons. Easily cured by nippering a small hole in the tube above the float bowl. I usually just do it at the bend at the top. You may also want to do a sanity check on your float level adjustment. I've done it wrong on occasion. Lets face it, float level adjustment is like the refrigerator light. When it's all closed up you don't really know whether it's on or off do you. Hmmm gives me an idea for a tuning accessory. A plug for the bottom of the float bowl with a tube that runs up the side of the carb. The float level would show up as the level of fuel in the tube.

Iridium plugs are really a waste of money on a dirt bike. They don't have any effect on performance. The reason for iridium plugs in automotive application is the iridium is extremely hard and erodes much slower from the spark then any other material. For car engines like the GM Northstar with supposedly no maintenance for 100,000 miles or a car that requires removal of the engine to change all the plugs it makes sense. For a single cylinder premix two stroke it makes no sense at all. Even platinum is somewhat overkill but at least they're cheaper.

I'd be inclined to fix the pinch bolt. The strength of the front end is really a combination of all the pieces working together. That and you really wouldn't want to snap the other just because it is carrying the full load now. Then you'd have twice the work and you'd have to fix it. When you assembled the bike you must have really laid into the bolts. When assembling a bike it's better to make sure everything is aligned properly and snug the bolts. Check the alignment again and go for the final tighten but don't overtighten. After a few hours of riding you'll find several of the bolts loosen up as the frame and forks settle in. Just give them the once over with the wrenches to snug them down proper after every couple of rides. I like the T-handle allen wrenches for this because they're fast but also give good tactile feedback of just how tight a bolt is. After a few cycles of this the frame and front end will have settled down and won't need more then the occasional snug. 70:1 works OK. A trials bike will smoke after putting around for a while because they tend to pool a bit of oil in the bottom of the crankcase. If you watch the world or national guys they'll rev their motors up before a critical part of the section to make sure they are running clean and purge the residual oil. As for the creaking, aluminum frames tend to creak. I've chased creaks in Beta frames since my '91 Zero and only managed to get about half of them. Usually I find bouncing on the pegs I get creaking from the frame at the skidplate mounts or the footpeg brackets. If you decide to chase the noise down don't try to fix it by just tightening the bolts as you'll end up having to fix them like your fork pinch bolt. try some lube on the frame where parts are bolted together as the creaking is pieces rubbing together under pressure. A squirt of WD40 or lithium grease can quiet down a creak not only locating it but often fixing it. The other thing to keep in mind is eventually the pieces that are creaking against each will wear in and the creak will usually go away on it's own.

Carl Sagan "Imagine if you will... Billions and billions of chickens crossing the road."

Hi Skidmeister, Are you having a cooling problem or just stressing over a something a little odd? Almost any time you have metal and fluid in contact in a hot engine they're gonna cook up something unpleasant. Could be residual gasket goo or assembly lube or myriad other things. If the fluid looks good that's a pretty good sign that there's nothing major going on. It sounds like this tan gunk is floating on the top of the coolant which would indicate it's not water soluble i.e. oil or some kind of polymer. First step is drain and refill with good coolant preferably something that is magnesium friendly (propylene glycol) like Engine Ice, Maxima Coolanol, or Silkolene Pro Cool. Ride for a while and see if there is the same amount of goo. It may be this is something that is just leaching out of the system and is relatively harmless. To be honest unless the thing is spitting steam out I rarely look at my coolant and then I'd have to see something really funky with the coolant to get me worried. A little scum on the surface I expect. Ewwwwwww!

Hi r2wtrials, I don't have to look down the intake throat. Asked Ron Commo Sr. while picking up a US world round minder's bike for my buddy. Ron said that the VForce on my '08 is machined out to 26mm for the Mikuni and he is talking to the Moto-Tassinari guy about making a batch machined out to 28mm for the Keihin carbs. Ron also said, and I have to agree, that unless you can ride a Rev3 wide open there's going to be very little difference between the 26/28mm throats. While I was there I did get to try a used 125 Junior WR bike he had in the shop for sale. Impressive. I tooled around the driveway for about ten minutes. Just to see if it would pull my fat ass I tapped it into third and snapped the throttle at a crawl and the front end snapped right up and stayed till about 3/4 of the rev range at which point I decided to stop goofing around and give it back before I hurt myself. Nice motor though. It obviously doesn't have the grunt of the 270 and I stalled it a few times (yes in third) but I could easily see riding this bike in an event and having a blast.

From the box the same one that fits the Sherco. I'll get the number off the box and let you know but don't be surprised if it is the same one as the '05. I have both the stock reed blocks for the '05 and '08 and they are identical. "giggity"

If the engine still spins and there is compression there it probably isn't that bad. Usually the result of no oil is a stuck piston and or damaged ring grooves causing the rings to stick. The above advice is about all you can do short of a teardown for a look.

Man that hurts. When the kicker went on my buddy's Raga he felt it wasn't right and parked it. I gotta give GasGas USA credit. They took care of him and it didn't cost him anything other then a few weeks of down time. Good object lesson though. If it doesn't seem right, park it until you know what the problem is.

Hi Rob, For me the biggest difference comes from cleaning up the tabs on the fiber plates. It makes the clutch engagement very smooth and progressive. I don't know if the 4T uses the same clutch but if it does then leveling and polishing the tabs is a big improvement. I wouldn't take the two springs out without cleaning up the tabs first. As far as feel the lever pull is obviously lighter but it isn't really noticeable until the end of the day when you realize your forearm muscles aren't pumped up making it difficult to hold the clutch in all the way through the section. I used to get finger fatigue as I tend to be a real heavy clutch user so at the end of the day I'd spend the last loop being dragged through sections because I couldn't hold the clutch in. That's not really an issue now.

Hey Ron! Yeah we miss you guys. Sonny couldn't get away for the world round and I just couldn't justify the cash to go by myself again. We were looking forward to hanging around with you but it just didn't work out. Congrats on the wedding. When we picked up my bike your Mom showed us the wedding pictures. Lookin' good. I see the young'uns are growing like weeds. Sonny and I are going up Saturday to pick up his new bike. He said he's going to go in the house first and ask your dad if he'll let me in. He told Sonny he'll prep the bike to keep me the hell away from it. When is Ronnie heading to Europe? I'd like to post something to the NETA website. Yeah I'm grooving on the new bike. I shed about 40lbs this year and I'm riding better then I have in a long time. That's why I was so psyched about the last event but it didn't happen and we couldn't even ride for fun so I couldn't let people test ride the new bike. Bummer. Hopefully one of these days I'll either make it down south or you guys head up New England way again. The local events are much more boring without the Commo clan to spice it up.

The best thing I did on my '95 was ditch the Dell'Orto for a Mikuni. back then though the jets weren't available for the Dell'Orto so it was kind of a necessity. With a fresh set of rings the '95 makes plenty of power and the '94 made a little bit too much for the average rider if I remember correctly.

Well it sounds like you worked the problem. Sorry you couldn't get it resolved. Here's where you get an idea of the engineer's mindset. For me that sounds like an irresistible problem. The kind of thing I find fun and can focus on to the exclusion of almost everything else until I have it figured out.

Very funny. Back story for those that don't know is the event was postponed and yes Skid has kicked my butt on his 200 in slippery conditions.

Yikes, it shouldn't be dirty at all. Maybe after a really dusty trials there will be some dirt in the intake bell but not in the float bowl. It almost sounds like you have some bad gas. If you're dispensing from an older gas can, especially a steel one there may be corrosion inside that sloughing off into the fuel. There were reports in the early days of the Verlicci aluminum frames of welding spooge in the gas tanks but that was years ago. Clean the carb, gas tank and purge the fuel system and dispense fresh premix from a new plastic gas can and see if the issue returns. I'd be surprised if that didn't fix it.

Oh yeah forgot to answer your original question. Sorry about that. Yeah the little brass tang in between the towers sets the float level. i.e. where the fuel level is in the float bowl when the valve shuts off. The other little brass tang that bumps up against the tower sets the float travel limiting how much the bike bouncing around can cause the floats to bounce around. The needle valve is really close to an on off switch. It's tapered so there is a lot of surface area for sealing and when it opens there's no benefit to having it open further then ~2mm. The extended float bowl is only intended to provide a deeper fuel reserve for situations where the float bowl may not fill properly because the floats are bouncing around with the throttle wide open for an extended period of time. Not really a scenario trials riders are likely to encounter on anything but a wide open loop trail full of whoops.

Make that "tubes" although the pipe usually melts one shut.