So Close!...
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Apologies if this is a daft question as I'm late to the party, but if you're blowing head gaskets have you checked that the head and the cylinder surfaces are perfectly flat?
Could be an opportunity to take it off, remove the studs and lap them both flat again on a sheet of glass (or engineers table) to be 100%
Ignore me if you've already checked this issue
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@nottsbiker
No daft questions bud. I haven’t recorded all my nightmares. But yeah, I’ve removed the studs and cleaned , checked and lapped. The second and third time the head blew are down to me, once using a gasket that had already been fitted, again when I used a copper gasket without fully understanding the process and not using spray sealant. The final time there was a scratch in the gasket that I didn’t expect or spot.I’ve fitted another new Athena gasket and torqued it properly. I’ve fitted a newly lapped 3bn head that’s tip top condition, and weirdly higher compression (12.5~13ml) than the 3mb I was using (14ml)...
The gasket blowing is only 1 issue I’m having. I have a black sooty plug, bogging down over 1/2 throttle and a nasty bog 1/4 throttle where the needle valve kicks in, that has been happening since I first got the bike. Oh and unburned oil in the chamber/ around plug. I’ve no idea what previous owners did to the carb. It was running on a 180 main jet though...
Every time I get somewhere another problem kicks in...New Athena gasket torqued properly, I’ve disconnected the oil pump and gone premix. Rejetted the carb to standard and am going to take it from there. Square one again 🥴
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Best I’ve had! After 15 mile test run...
Same plug, different light...
Was revving ‘quite’ cleanly up to 9000rpm on 1/2~3/4 throttle. Just a little snaggle @ 1/4 throttle...
updated ran the engine up to temp for 15 mins on tickover and the plug was black and wet. I’m @ 1 & 1/2 turns on the airscrew. I will try up to 2 turns, then maybe go down to a .20 pilot jet. I have some genuine Mikuni ones now. The cheap fleabay ones are worse than a joke. I brought 10 varying from .10 upwards and they were all the same. Even though they were stamped
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@Calum
Cheers...I forgot to say, I blocked/bypassed the power jet as well. I was getting bad random bogging above 1/2 throttle with loads of smoke. It’s stopped so far. I just wanted to cut out as many variables as possible and tackle them one at a time. I even bubble wrapped the ignition control modules under the seat in case they were getting a bashing and it was electrical...
Oil pump was definitely splurging
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Took it for a 70 mile test run today. The head gasket is holding in there!..
As it was running well a day ago, I thought I’d put the needle down a notch (from middle) to the 4th notch down, where it’s supposed to be according to the manual. The plug is a richer chocolate colour but it started bogging again. So tomorrow it’s back to the 3rd, middle notch. Make sure it runs as smooth as it was before, then address the pilot jet/airscrew mixture...
I’d never believed a single notch could cause so much change! Wish me luck...
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more variables:
Found 2 new potential problems: 1, the wires for the sidestand kill switch may of been crushed by the seat. 2, I had to fit an inline fuel filter because of the state of the tanks inside, it has been creating a ‘locked in place’ air bubble. I don’t know if it’s been affecting flow at high revs and causing ‘bogging’. I have managed to finesse the air out by holding the tank up and keeping the fuel line vertical...
My next test ride will tell...
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Best colour yet, ever! This is with the needle in the middle slot, also with the airscrew turned out 3 full turns. That is fully open when you look into the air jet!...
Below:
This is the plug that’s been brought up to full temp on tickover only, remember that this is with the airscrew wound full out...
Wet n black! I don’t know why the standard 0.225 pilot jet is too rich on my particular bike, but it is. I have a 0.20 Mikuni jet I’m gonna try tomorrow. Wish me luck
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Found another potential yesterday, the long breather pipe that hangs down on the kickstart side leads to a hole at the top of the ‘tube’ that the needle jet fits into. (I guess it’s to let the fuel level go up and down inside the jet, equalising the pressure, maybe? Fluid won’t rise in a closed environment, like an upside down cup in water) where the slide housing joins there is potential for mischief. My gasket is so compressed I have to use sealant. I’ve tried hermatite red and silicon. The silicon was kinda vulcanised by the fuel at the bottom of the slide where the breather pipe join is. So I’m going with the red but I’ve had so many inconsistencies I really want a new gasket. Anyone know of?...
I think the vent has been causing some of the mid throttle bogging and inconsistency... -
Went down to a .20 pilot and it still ran wet plug with the airscrew fully out! Since put in a 17.5 and it ticks over well, the plug is still slightly black but not dripping wet at 1.5 turns...
The proof will be in a test ride though...
I’m using this thread as a memory diary, if I don’t write it down I forget!
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@calum
I’m not sure why you think that is super hot bud, 90* is perfect running temp I think. If it’s doing it while under load at high revs is even better! You’re running 200 twin radiators aren’t you?I’ve managed to reign mine in a bit. I put another radiator on it that I managed to finesse back into usefulness. I straightened some fins and removed the outer edge of the worse with a Dremel type tool.
My old radiator had so many fins folded over on the inner side that it wasn’t funny! Why the inside gets the brunt of it I don’t know. I’d of thought that it would be the outer ‘wind in’ side that caught it?... -
@spookdog It went mental on Sunday 100 degrees centigrade under very light riding. I came to a stop at the traffic lights and the engine just started to rev it's nuts off on its own. I killed the engine (nothing) turned the ignition switch off nothing. Had to kill the fuel in the end.
So yeah, it just seems to run WAY too hot that it's igniting on its own
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Since I’ve had the ‘new’ radiator on I’ve had a lot better temps during the hot days recently. I’ve swapped out the standard tailpipe for a BigOne that’s been laying around, this seems to be beneficial as well. It seems to be running even cooler. Not sure why...
The plugs been dry since I fitted the 17.5 pilot jet, the midrange seems good as well going by the plug. Top end/main jet is still buggered. The last two times I snapped the throttle open fully I had heatseize symptoms. Both times I whipped the clutch in and coasted to a stop, both times it started up straight away. I haven’t been in a position to recreate the symptoms to see if it was a genuine heat seazure (sp?) or a totall bogout due to main jet being wrong. It’s a 210 ATM, it was a 180 before...
Problem on top of problem after problem being an invisible problem 🤯
Oh well it’s all in fun and we live and learn while the World falls apart around us!
