Fuckin motor

[Katana]

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

[Captain Chaos]

faulty compression tester?

[Markz9]

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

[Katana]

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 

[Captain Chaos]

if pistons and valves are known good, leaves only cam timing.

[Pegleg]

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. 

[Guest YoshiJohnny]

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?

 

[vizman]

mouse nest in your pipes

[boilerdude]

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.

[Katana]

Minimum  compresion according to the manual is 175 so 140 isn't good

[Captain Chaos]

someone put shorter connecting rods in the engine?

[Bandit31]

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

 

 

[boilerdude]

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...

[TiZiK]

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

[webby7]

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