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Managed to get my hands on an old 80s dragbike frame, it's been sitting at the back of the shed for a while while I kept looking at it wondering how to get the very tall xs engine in it, Finally decided to take the plunge and drill the frame as with the bottom mount above I couldn't get the...

If you go to 17 1/2 minutes on this video then watch this one 3 weeks apart same petrol, I had 3/4 gallon left bike not touched, running perfectly 3 weeks ago one of my fastest times now missing from running too rich, such a big difference just can't understand how.

Was struggling last weekend with plugs and a fueling problem, I thought I had an engine problem so just done a compression test, found I have around 200psi on both cylinders, is this too high for standard fuel? or is it something else.

Can anybody explain in simple terms how to time the cam, I'm going to have a go at it with the 250-40 I have but not sure how to do it, do I set the tappets .040 and wait for the valve to start moving or set the tappets to 0 Plus there is lots of information on regarding the cam for the...

Keep seeing this xs on eBay only selling the pipes, it's got to be one of the strangest xs's out there looks like a cross between a Honda c90, flattracker and a chop.

Has anybody else found the 250-40 raise the compression so much it's vertually impossible to turn over let alone start, I have je pistons I've tried this cam in this engine several times now keep hoping the motorcycle fairies have been in and made it better but every time I put it in I can just...

Thought I would start a thread on my bike, I had been watching sprinting for a few years before I had a go, I took my 750cc xs650 down and got a time of 13.68 without even topping 100mph, took a break for a few years then joined the nsa and have been taking part ever since, when I first started...

Which do you think would be better 1mm over kibblewhite valves or 2mm over xv valves, if it was just down to size the answer would be obvious the kibblewhite are stainless so should have smoother flow across them against the heavier steel larger xv valves

I've been looking at the Mojave tanks recently, was thinking about one for my xs but noticed there are several different shapes on the tunnell, do they all fit the xs frame or do I need to look out for a certain one , the xs seems to have a very steep frame angle compared to other bikes as I've...

I've just ordered some shims to index my plugs, I thought I would look up the correct place for the plug to end up and ended up with 4 different results Facing the inlet Facing the exhaust Facing across the piston And facing away from the inlet They can't all be right, which is it supposed to be?

anybody spot what differs from the description on this bike? http://cgi.ebay.co.uk/ebaymotors/1971-YAMAHA-XS650-750-ROAD-RACER-FORMER-MULTI-AHRMA-CHAMPIONSHIP-BIKE-/271773727191?ViewItem=&item=271773727191&forcev4exp=true#ht_500wt_1180

as the title says, does anybody recognize this cam, I thought it was a megacycle 250 40 until I bought one, it's nothing like it the lobes look to be much larger, only identification is an 8 78 which I assume is the date it was made and a c on the outer lobe.

Has any body got pictures of the lillie head with the porting and combustion chamber? or the Shell and Branch heads, would be nice to actually see them to compare them rather than read and guess at the differences.

Question for the carb specialists, When under full throttle I have a slight hesitation when changing gear, the bike is running slightly rich, would the hesitation be caused by too much fuel until the engine catches up or too little? whilst I realize I need a smaller main jet, I'm not sure which...

I need a good pair of 256 rods, don't need the complete crank as they will be being put on a 447 crank,

Does any body know the best carb size for the xs, after market slide carbs not the cv, I've read about some racers going as large as 38mm, but with only a 34mm inlet track is this a waist? or will it compress more gas into the cylinder as it passes?

Anybody have any gearing recommendations for sprinting/Drag racing, currently using 18/34 running 12.69 best time,

Just had a pair of pistons come with their barrels so definitely from an xs, standard xs piston by the side for comparison, but not the same way around, they are for 533 rods, made by Mahle pistons in Germany, 80mm bore, no lip around the edge but are tapered on an angle and when mated to the...

I've seen a few xs's running without the head steady has anybody on here done this? has it any effect on the top end? engine wear ?

Does anybody know anything about this bike?, just found it on Hoosracing customers bikes http://www.hoosracing.com/customersbikes.html think you might need a magnifying glass as the picture is so small