Before putting my bike back together I am checking the tolerances of the crankshaft to see if everything is okay. I checked the clutch side of the engine cage side clearance and it was good at 0.024". When I checked the flywheel side however, it seems to be far too wide at 0.040". This doesn't seem right, but perhaps this gap closes up upon refitting the flywheel? Maybe it wasn't pressed together correctly? Or maybe I need to recondition the crank? _________________ MC21 Honda NSR250. TYGA 300 conversion.
Here are some pictures to illustrate what is going on. It almost appears as if the bearing isn't pressed on far enough by the workshop that did my bottom end last :/ _________________ MC21 Honda NSR250. TYGA 300 conversion.
According to that the lateral play is out by quite a bit, the service limit being 0.85 mm where mine is ~ 1.02 mm. This has nothing to do with the bearing I don't think. I'm thinking that the crank wasn't pressed together far enough or the thrust washers are too thin. How could this be? The crank was only reconditioned 8,000 km ago.
The main bearing has nothing to do with the conrod end float as you say. If the crank has only just been rebuilt then you need to find someone that will do it properly this time around.
The big end thrust washers do tend to wear but by very small increments. I'd say its been rebuild incorrectly. Did you not check it before installing it into the cases after it was rebuilt? _________________ If I have to take the carbs off once more...
I did not check it. I took the whole engine (bottom end and gearbox, without cylinders), in a box, to a workshop. I told them it needed new seals and they assured me they rebuilt it and assured me that it was within spec.
I took it home, and put the top end on it and back in to the bike. That was 8,000 km ago.
Well this time you'll be able to see for your self that its in spec. Always better to check yourself. _________________ If I have to take the carbs off once more...
Talking of cranks.. i am just in the process of removing mine for a rebuild following a suspected crank siezure.... I'm thinking of buying the bearings and having the crank rebuilt by a local guy who has built plenty of cranks although not NSR's. However I have also looked on the Tyga website and they sell a replacement bottom end kit which includes a new crank. Its a bit pricy at £550 but by the time you have bought all the seals bearings, new rods and paid for the rebuild there might not be much in it.... the question I have is... the part number for the new crank is 13000-KV3-950 but this number doesn't show up on the parts list on this forum..... the number against my model (NSR250R9N) is 13000-KV3-900, can anybody shed any light ?...thanks.
Don`t forget shipping on top of that, and a crank`s a hefty old lump too. You should also factor in another 20% or so in import duty and VAT (on parts & shipping combined!).
You might not have to pay it if it sneaks through, but it`s bit of a shock if you`ve not allowed for it as a contingency.
£550 can very easily become £700+! _________________
There`s no cure for stupidity… but with the endless supply of stupid people around me, I must be close to finding it!
Parts are 4% Duty plus 20% VAT added after shipping and the price of the kit. If you do get charged then it works out around £750-800 total into the UK. _________________ If I have to take the carbs off once more...
anonymous.shyster wrote:Here are some pictures to illustrate what is going on. /
I cannot locate said pictures. Am I being stupid?
I am not quite sure what you are talking about....
Is the measurement you are talking about from the inside of the crankcase to the outside of the main bearing?
If so, then I'm not too sure that it necessarily means too much anyway. But I am not 100% sure here.
If the lateral play between conrod and thrust washers is OK (0.55-0.75mm) and the anti-spin pins on the main bearings line up with the slots in the cases, then you are probably OK.
Pictures or better description required really.
I am guessing that you don't really want to take the barrels off to check the lateral play of the conrods. But perhaps this may be good for peace of mind?
<edit>
Oh, I think I couldn't see the pictures because I wasn't logged in. D'oh!
So you can basically ignore what I have said here.
When pressing the cranks back together, I would put put a couple of 0.65mm feeler gauges in place to ensure correct lateral play.
/<edit> _________________ [color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...
Last edited by TuckerBag on Mon Jan 02, 2012 8:55 pm; edited 1 time in total
He has the crank removed and is talking about the end float of the con rods against the trust washers. _________________ If I have to take the carbs off once more...
If it is the same workshop that built your crank as the ones who jetted your bike i would double check the crank again as they were found out to lacking in know how .
Send the crank to a trusted mechanic for a check over , beter safe than sorry .
What are the simalarities between a 10 foot crockodile , an expired condom and a dodgy crank ?
Neal wrote:
What are the simalarities between a 10 foot crockodile , an expired condom and a dodgy crank ?
Actually, the first known contraceptive was crocodile dung, used by the Egyptians in 2000 B.C
Condoms are a contraceptive
And having a dodgy crank can keep you in the garage till the small hours, therefore, also acting as a contraceptive.
Just felt like being a bit stupid today _________________ [color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You cannot download files in this forum
