Katana Posted March 9, 2016 Posted March 9, 2016 Ok I have got my finger out my arse and started playing with my Kat again it's got a bandit motor in. I got it running on all four and it's still flat as a fart and won't Rev over 4000 rpm so did compresion check and 130/140/150/150 I have had 5 different sets of pistons and barrels on three different heads 4 different wiring looms 5 different cdis 4 different sets of carbs I'm getting pissed off now I really need to know why this has no compresion I reground the valves will someone please tell me why it has no compresion Quote
Markz9 Posted March 9, 2016 Posted March 9, 2016 you need to be a bit more logical with testing first try the compression tester on a know good engine make sure its ok then spin the engine over on each cylinder and record numbers I don't think those numbers are too bad its more important they are close to each other if you put a little oil in each cylinder 5ml spin again if its a higher reading this time the rings are shot sounds more like miss timed cams to me may be 1 tooth back this means valve open when its should be tdc = no power good luck 1 Quote
Katana Posted March 9, 2016 Author Posted March 9, 2016 I think the 8 times its been striped I would have got it right at least once as I said it's had 4 different sets of Pistons and I have tested compresion tester Quote
Captain Chaos Posted March 9, 2016 Posted March 9, 2016 if pistons and valves are known good, leaves only cam timing. 1 Quote
Pegleg Posted March 9, 2016 Posted March 9, 2016 Is the fuel in the tank fresh? Doesn't like sitting too long. I've been there. Had similar problem on Trumpet I bought cheap. Previous service invoice showed tappet shims had been done. Cam timing was out. Quote
Guest YoshiJohnny Posted March 9, 2016 Posted March 9, 2016 Exhaust blocked, low compression is either down to cams or timing (but Dave Dunlop has done the timing?) or using 8 sets of used barrels and pistons... is the motor out? Quote
boilerdude Posted March 9, 2016 Posted March 9, 2016 Just so we're all on the same page here. You did the compression test HOT right? Because if it's cold 140-150 is a good reading. Quote
Katana Posted March 10, 2016 Author Posted March 10, 2016 Minimum compresion according to the manual is 175 so 140 isn't good Quote
Captain Chaos Posted March 10, 2016 Posted March 10, 2016 someone put shorter connecting rods in the engine? Quote
Bandit31 Posted March 10, 2016 Posted March 10, 2016 Mate of mine had fresh engine built, didn't run right, turned out the piston rings supplied were slightly the wrong size... other than that, my fav: https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test Quote
boilerdude Posted March 10, 2016 Posted March 10, 2016 compression according to the manual is 175 HOT!!! WITH THE MOTOR HOT!!! Im trying to make sure you HAVE THE MOTOR HOT!!! when you check because IF YOU DONT HAVE THE MOTOR HOT!!! you're not going to get that 175. THE MOTOR NEEDS TO BE HOT TO GET AN ACCURATE READING. If it's cold and you just do the test cold then YES you are going to see more like 150... Quote
TiZiK Posted March 10, 2016 Posted March 10, 2016 You are holding the throttle wide open during comp test right? Do yourself a favor, perform a leak down. It'll tell you what's up. If cam timing is off, you'll know. If rings or valves are shit , you'll know. Much better test than a comp test. Good luck 2 Quote
webby7 Posted March 14, 2016 Posted March 14, 2016 (edited) Hi don't know if this is going to help but I had the exactly the same problem with B12 Kat, I tried new coils, new CDI, new set of carbs, Compression tested, Valve timing, in the end I solved the problem, it was the float heights even thou they were set correctly the B12 engine sits at a different angle in the Kat frame slightly lent more forward so not getting enough fuel. played with the standard carbs for weeks got it running pretty good but not 100% so tried a set RS38 carbs. problem solved. Edited March 14, 2016 by webby7 2 Quote
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