Rare Scottish Tree Badger

Do you run with no tickover? If so, which method do you use ... backing off the idle screws, or richening the air mixture screws (pilot circuit)? ... I'm not saying this is your cause of top end failure, but it will make a difference when coming off the throttle after WOT to no throttle. Excess heat, but you know that. ... Does the other piston ever show signs of overheating? Better to do a leak down test on the rebuilds so you can say "I don't have an air leak". (Obviously, one can develop). That plug will be too 'hot' for your riding conditions. ... It's working temperature is a lot lower and it won't remove enough heat. I would stick with the 9s, you don't have an increased compression, but you will be running hard at mostly between sea level and 1000ft I guess. As mentioned earlier, that needle setting seems lean for 1/4 to 3/4 throttle which is going to add heat when you're in that range. ... Have you done any plug chop runs? Have you tried bigger mains than the 260s with the power jets? You would have noticed performance problems and maybe plug fouling if you'd been running too rich. Arm yourslf with 310s to 340s, but I still say stick with the 9s 'till you sort the overheating out. You're also putting a lot more stress on the engine than it was designed for. (More weight to pull and MX/ Enduro are tough on the motor). RD or Banshee gears? Any of those cooling aids that you mention are going to be an improvement over stock. ... Some other things that are worth thinking about are the Pro Design impeller (water pump) for reliability and increased flow. And some better coolant, such as Engine Ice or Redline Water Wetter. (I use Engine Ice and am about to get the Impeller). Most likely after IMO, as you would have felt the lack of performance with blown out reeds. Did the reeds ever fail like that with any of the other engine failures? What premix ratio do you run, and what octane fuel? Rare.

Might be worth investing in an EGT monitor. ... I wouldn't advise changing to BR8s until you get your temperatures down. You using this for MX? Rare.

Yeah, good ones! . Rare.

... More! Rare.

......... . Rare.

Also check that your fuel tank breather from the filler cap isn't partially blocked causing a vacuum and reducing flow. Rare.

Ton, Don't get too excited. ... After two burn downs, it turns out that Europe's octane numbers are purely based on the R.O.N. (Research Octane Method) and the American rating is an average of both R.O.N. and M.O.N (Motor Octane Method). 98 R.O.N. is the same as 89 M.O.N ... added together and divided by 2 = 93.5 95 -------------- " ------------- 86 M.O.N ... ------------------ " -------------------- 2 = 90.5 So be carefull and do some checking before you burn down thinking you've got 98 octane when you've actually only got 93! I'd like to be proved wrong. ... Could be old info that I've been looking at. Rare.

I stand corrected . Sorry Wheatchex for contradicting your explanation. It seems that I was under the wrong impression of some of the heat range properties. Beem me up Scotty! Rare.

I see you've edited your first post. ... Better to start on a new line with "EDIT: ..." or explain in a fresh post. Anyway, so it's not a WOT (mains) problem. If you're backing off the throttle for your cruising speed, then it's more likely a jet needle issue (1/4 - 3/4 throttle). ... Try moving the needle to a richer setting - moving the clip down from 3rd from blunt to 4th from blunt. It does sound like fuel starvation as others have said. ... You could check your float levels. The factory doesn't jet for removal of the snorkel, so it might be wise to go up one or two sizes on your mains. Rare.

Every motor's different. ... Yours is maybe breathing better. I asked about your premix ratio to see if you were running a lean fuel to oil ratio, but you're not. I would do the plug chop with the 290s first. ... Better to be too rich than too lean at WOT. Warm up the bike on old plugs and swap in new plugs for the WOT run. Here's a pic of cut plugs. ... The one on the right is cut with a grinder and the left is with a hacksaw. Much neater with the hacksaw - cut through the threads (about 5 threads from the washer) until you feel the teeth against the porcelain, they'll just slide and not cut, and then move round the plug a bit further. Once all the way around, the upper threaded portion with the earth strap will just pull off. * Rare.

What you've said there, in theory, is correct. ... What premix ratio are you using? EDIT: Scott's given you the 'in practice' situation in the thread above. ... Good info. Rare.

Strange that it clears up in 3rd. ... With such strange behaviour in different areas it wouldn't be such a bad idea to check out the reads. Rare.

I've often read that 0.018" is a better gap setting to go with for higher compression motors so as to prevent blow out of the spark. ... Not sure about stock . Rare.

That sounds like a substitute for rejetting . ... Running rich in warmer weather and leaner (more heat) in colder weather.

You've got pipes tho'. ... His bike's got stock pipes. Banshee~, this is a quote from Streppe about reading the plugs: "You won't find any soot out near the insulator nose, on a plug that's running hot enough to keep itself from fouling, because temperatures there are too high to let soot collect. But the insulator is much cooler deep inside the plug body, and coolest where it contacts the metal shell, which is precisely where you "read" mixture strength. Look far inside a plug, where its insulator joins its shell, and what you'll see there if your engine's mixture is too rich is a ring of soot. If this ring continues outward along the insulator to a width of even a millimeter you can be sure the mixture is rich enough to be safe, and too rich for maximum output. In most engines best performance is achieved when the mixture contains only enough excess fuel to make just a wisp of a "mixture ring" on the plug insulator." Rare.

.... Sorry, but that was just tooooo funny. Have you tried a compression check to rule a few things out? How do you know it's had a top end done 30 hours ago - you only just bought it, so you wouldn't know what punishment it's been through. EDIT: It does sound electrical tho'. ... Have you got a cdi that you can swap in? And also a stator. Rare.

It comes out from above, but there's an externally threaded bolt (more like a massive Allen screw, 17/19mm?? accross) that needs unscrewed before the bearing will come out. Rare.

What lasts for thirty seconds? And is the throttle pinned? ... Need a better explanation . Spark plugs tell you anything? Rare.

How are you reading your plugs? Have you done a plug chop at any stage of trying different jets? What size jets did you try - all sizes upto 290? Are they B8ES/ BR8ES plugs that you're using? Since you don't have an air leak (at the only places you've worked on, i.e. carbs and boots), and most of the guys have suggested that around 240 mains is about where you should be; I think a fresh set of plugs, 240 mains and a plug chop run are in order. ... Look for a clear white porcelain color, like new but not grainy/ porous and a 1mm ring of carbon at the base of the porcelain where it joins the shell of the plug. This is seen the best by cutting the threads off the plug - hence 'plug chop'. Rare.

Sorry to hear about the loss of your 'pal'. ... How old was he? Rare.

Due to the properties of Iridium, the spark plug's centre electrode can be made with a much smaller diameter than with platinum, gold or gold palladium and copper/nickel types without sacrificing service life. The spark plug's potential difference is more concentrated at the tiny Iridium tip and hence less 'spark jump' voltage is required - this can be as much as 5,000 volts less than with standard plug types. Ignition is improved and less strain is placed on the ignition system. Benefits of improved ignition/combustion include better fuel economy, increased power/acceleration and especially better throttle response. Disadvantages are that they're a lot more expensive than standard plugs, and can be more difficult to 'read'. Rare.

As mentioned above, if it's not your plugs then try checking your reeds. Quote: "but how do i check the reeds?" ... You need to remove the carbs and then each reed cage is held on with 4 socket head capscrews (allen head bolts). Take out the cages and look for any of the following: Reed petals not closed against the cage, broken reeds, cracks/ chips, distortion, or even a bit of dirt or something else stuck between the petals and the cage. BR7s are a 'hotter' plug than a BR8 which means they reach their ideal working temperature at a lower temperature in the combustion chamber. Only use that type of plug if the motor never runs at high loads or high temperatures. (unlikely 'cos it's a 'Shee!). ... Using a hotter plug in the wrong conditions can lead to overheating and preignition. Rare.

The following are some guidelines for your situation taken from an old FAQ of BenBB: Remove snorkel:1-2 sizes larger on the mains, adjust airscrews Remove airbox lid:1-2 sizes larger on the mains, adjust airscrews Add K&N air filter:4-6 sizes larger on the mains, adjust airscrews, add one size on pilots if necessary. Those figures say anywhere between 6 and 10 sizes (260/270 -300/310). ... Without pipes, you'd be around 260 at the most IMO. Do a plug chop and see what your plugs tell you. I would think that it's your stock pipe that's restricting your higher RPM/ power. ... You've opened up all the intake side of things to get more air in, but it just can't get out. Get yourself some aftermarket pipes to suit your riding style, and your bike will be massively improved! (Remember to jet up again ). Rare.

Too quick! .... You hit the gate with your front wheels and are now eating dirt!!! Rare.

Rod, it's back up again. But it looks like a fresh start. ... I had a look earlier, he's got some great riding areas on his doorstep! Rare.