Trying to fix an issue
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@Stevie-Wonder Glad your carb rebuild went well.
If you want to pin your PV for test purposes, cut down the shank end of an old 4mm drill bit to about 35mm; this obviously locks the pulley in the open position but can't go anywhere when you put the pulley cover back on.
I keep one of these with the tools I carry on the bike as "get you home" in the event of a PV cable breaking. Just remind yourself to remove it before reconnecting the cables/servo as I think the servo would be powerful enough to wreck its own internal gear train if you switched on the ignition with the PV locked in place like this.
Also have you ever replaced the HT lead? I had a high rpm misfire on my 1990 and it turned out to be this; took about an hour to change so the bike wasn't at operating temperature by the time I put it back together and tested it, but it was STILL noticeably faster/more responsive than before I changed it (I nearly flipped it pulling out of my driveway
).On the stock coil you can cut off the very top of the plastic case (i.e above where the actual lead fits into it), get the old lead out (it's glued in), then clean up the output and solder on the new lead for a really good connection.
Looks a bit messy as you have to tape it up afterwards and seal with silicone but in practice, usually a better option than a LBS replacement coil as these often have the wrong primary and secondary resistances for specific bikes (and BTW it's also worth measuring these).
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@HOTSHOT-III
Good idea that bud, I think I used a twig once when I was riding in a Forrest
Not sure if you knew this though but one of the ignition cycles when you turn on/off the bike leave the PV in the open position instead of closed, once it’s like this all you’ve got to do is unplug the servo via the 4-pin plug by your radiator and you're set
As for the HT lead, nah I haven’t. I have been looking for an excuse to buy a nice new red “race” ngk one for a while though….
What’s on there is an old NGK one or OEM original to the bike
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The power valve is open at default any was. It’s only when you start the bike that it ‘closes’...
You could pull the plug before starting the engine...You do have the power valve set at open/flush when the engine is off don’t you?...
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@SpookDog said in Trying to fix an issue:
The power valve is open at default any was. It’s only when you start the bike that it ‘closes’...
You could pull the plug before starting the engine...You do have the power valve set at open/flush when the engine is off don’t you?...
Yep, admittedly I haven’t checked but I doubt it’s just magically jumped out of place since I last set it
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How long have you been having this problem? Hasn’t been since you last set up the power valve has it
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Since the first or second time I took my carb off to inspect the float valve when fuel was pissing out the overflow
I just took the bike out and I’m certain the powervalve is operating as should be and sat in the right place.
I do however have a sneaky feeling the air boot isn’t properly sealed, causing an air leak.
I’ve also found a little pin prick hole in the carb warmer hose that sends coolant into the carb.
I took the bike out for a little ride, I say little because I got less then ten minutes ago and the temp gauge was already 3/4 across the dash and climbing.
There where a couple times where the bike just shot off like a rocket whilst the valve was pinned but other then that It’d get to about 6-8k (at a guess because remember I don’t have working clocks) then struggle to go any further.
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Did you ever fix the leaky crank seal on the flywheel side, bud? Something still ain’t right if you’re getting that hot. I used to have temp troubles till I sorted out my jetting. Even my bike has been running cool during the worst of the heatwaves. While there is water in the radiator anyways
I’d be looking for any air leaks. Spray on either wd40 or (I use) solvent brake/clutch/carb cleaner. The revs will lower/settle down if it temporarily blocks an air leak...
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@SpookDog said in Trying to fix an issue:
Did you ever fix the leaky crank seal on the flywheel side, bud? Something still ain’t right if you’re getting that hot. I used to have temp troubles till I sorted out my jetting. Even my bike has been running cool during the worst of the heatwaves. While there is water in the radiator anyways
I’d be looking for any air leaks. Spray on either wd40 or (I use) solvent brake/clutch/carb cleaner. The revs will lower/settle down if it temporarily blocks an air leak...
Nope, turned out there was no crank seal. The bike held and made good compression when I did a compression check.
To back this up when I crashed my bike the issue magically resolved itself and the bike suddenly ran beautifully, as good if not better then the day I got it.
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The crank seal failing wouldn’t affect bore pressure. That’s purely between the piston&rings and the head. It would totally fuck with your mixture & running though. It’s such a cheap and easy fix it’d be silly to ignore it. I seem to remember you saying the revs settled down when you sprayed it before?...
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@SpookDog said in Trying to fix an issue:
The crank seal failing wouldn’t affect bore pressure. That’s purely between the piston&rings and the head. It would totally fuck with your mixture & running though. It’s such a cheap and easy fix it’d be silly to ignore it. I seem to remember you saying the revs settled down when you sprayed it before?...
Nah, I sprayed a couple different flammable substances and it made no difference.
And ahh okay
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@Stevie-Wonder
My bad, no worries ... -
@SpookDog
No worries man, I wish it was that, it’d be an easy fix then. But the fact the issue solved itself and ran perfect for a good month after I thought it was that rules out LH crank seal being the problem entirelyIt’s worth noting I tried the old trick of running the bike with the choke on to richen things thinking this might cause stop the heat building and possibly make a difference to how the bike was running.
Unfortunately though this made no difference, temp still carried on soaring and still reluctant to go through the revsThe only place there could be an air leak is where the rubber boot joins the air box… this would then cause a lean running engine.
This leaves me some questions though…
I’m led to believe where the air boot meets the air box doesn’t have to be an air tight unit, is this right?Being a water cooled engine doesn’t this mean as long as there’s sufficient coolant, your radiator and water pump hoses etc are all in good working then even if you had an engine that was run very very lean the heat would be managed?
Or would it be more a case that the cooling system isn’t up to the job to handle those conditions?
As it stands to sort this I have to
- Check there’s enough coolant (I can’t imagine having lost enough to make a difference however the carb warmer pipes are still prone to odd drip or two even when I plugged them so this could have built up over time, always worth checking).
- Check water pump is working
- take zorst off and fit new carb warmer coolant line (as one has a pin prick hole from being nipped by the hose clamp)
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Have you not checked the radiator level yet? I would check that first job. Second would be swapping out the thermostat. Running lean made my bike run ‘hotter’ but not that hot!
Also check for overflowed coolant at the expansion tank filler. Sticky crap below it on the chain guard and swing arm... -
@Stevie-Wonder Air leaks before the carburettor are generally not an issue since you have a carburettor. By that I mean, the venturi effect created due to the air meters the fueling. Since you're only running at normal atmospheric pressures you can rule this out.
With regards to coolant and engine temp, if it's running so lean that the engine detonates then the temperature will spike before/during it seizes. By the time the temperature moves it'll already been too late. You have to keep an ear out for detonation in that case.
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@Stevie-Wonder a lean condition seriously affects the temperature. A main jet 1 or 2 sizes too small can easily make a difference of 20 degrees so an air leak caused by a split rubber can be catastrophic.
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Okay wicked, so we can rule out the rubber boot to the air box not being airtight as not being an issue.
Also the jetting in the carb is the exact same as it’s always been since I’ve had it so jetting shouldn’t be an issue, the only thing that could’ve changed slightly is the air screw.
I’ll keep an ear out for detonation as that’ll give an indicator to wether it’s the engine running lean being the problem or it just being a cooling problem.
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@Stevie-Wonder
Did you check the radiator coolant level?... -
@SpookDog said in Trying to fix an issue:
@Stevie-Wonder
Did you check the radiator coolant level?...Nah after I took it for a ride I just put it back and haven’t touched it since.
Been saying to myself I’d do a little bit here and there after work but this heat has been killing me off and leaving me so fucked where the only thing left to do is have a beer and chill out.
However today I’m going to go through that checklist today and try do as much as I can.
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@Stevie-Wonder Ptsch! What sort of attitude is that! This is perfect trail riding weather. You're young, you should be full of energy smashing it out.
