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Post by markg64 on Jun 23, 2020 15:39:46 GMT 1
Hi all, First and foremost I am just asking for views on these straight cuts and am no way having a go at our Norbo in any way whatsoever. Used an oil pump gear from him in my 443 lc and after 3 minutes of running it my clutch cover was full of filings. I have since found out that my engine has banshee straight cuts and apparently they do not use oil pumps hence the shredding of my gear. (Pic attached) I've been looking at various other ways round, Nova/ Mad biker (which are nova as well as far as I know) and norbos ones. I've messaged norbo today about these and it seems the case that he has had about 120 sets made with no come backs at all. Price wise, Mad biker and nova around £430, Norbo's are about £130 cheaper than the nova ones, and I need to get this engine up and running and more importantly "safe", the last thing I need is it going bang if you know what I mean. Have any of you used or are using these and how have they been in your opinion..... I just need to get this right Cheers Mark   |
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Post by LC_BOTT on Jun 23, 2020 15:56:15 GMT 1
Wow that's bad, it looks to me like it was too large a diameter? I'm no expert and purely guessing, as not seen or heard of it before, was it hardened or just plain alloy?
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Post by headcoats on Jun 23, 2020 15:58:38 GMT 1
Fook!
I had straight cut gears from Wicked bikes from USA with similar results
I had them independently checked for their hardness and it turned out the larger gear hadn't been hardened at all FFS
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Post by markg64 on Jun 23, 2020 16:14:16 GMT 1
It's just an alloy gear, should have been fine just running a pump, it just couldn't have meshed with the banshee stuff ( as they dont run pumps)
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Post by midlifecrisisrd on Jun 23, 2020 16:31:07 GMT 1
It's just an alloy gear, should have been fine just running a pump, it just couldn't have meshed with the banshee stuff ( as they dont run pumps) But whether a banshee runs an oil pump or not the gears should be the same Steve |
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Post by headcoats on Jun 23, 2020 17:22:51 GMT 1
Could it have run on a standard plastic gear ?
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Post by oldbritguy on Jun 23, 2020 18:07:14 GMT 1
If you run straight cut primary gears then you will also need a straight cut drive gear for the pump. STD cut gears are helical cut hence the critical backlash numbers and the oil pump gear is cut/moulded to match.
If you mix helical and straight gears then the softest material gear will shred.
Was the damaged gear straight cut too?
As most users of straight cut primaries do so for big power engines and probably run pre mix, you may need to get a gear made unless as you say Martin at Mad Biker can supply one
Hopefully someone will come on and provide a solution for you soon
John
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Post by stusco on Jun 23, 2020 18:23:21 GMT 1
In Norbo’s shop it does say the straight cut oil pump gear matches the straight cut primary’s He supplies,maybe yours are a different ratio
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Post by flames on Jun 23, 2020 19:41:54 GMT 1
Christ!!! Sometimes bolt on / in goodies aren't as simple as they seem. Never would have thought something like that would have happened!
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Post by markg64 on Jun 23, 2020 19:53:28 GMT 1
If you run straight cut primary gears then you will also need a straight cut drive gear for the pump. STD cut gears are helical cut hence the critical backlash numbers and the oil pump gear is cut/moulded to match. If you mix helical and straight gears then the softest material gear will shred. Was the damaged gear straight cut too? As most users of straight cut primaries do so for big power engines and probably run pre mix, you may need to get a gear made unless as you say Martin at Mad Biker can supply one Hopefully someone will come on and provide a solution for you soon John John, it was a straight cut oil pump gear going on to straight cuts. The primaries I have are banshee and I didn't know that at the time, but banshees run pre mix so no pump gear available for them mate |
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Post by markg64 on Jun 23, 2020 19:55:43 GMT 1
Could have been the pitch as banshee are american and still use imperial not metric (still in the dark ages) lol
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Post by Deleted on Jun 23, 2020 20:54:06 GMT 1
I doubt it would be the pitch, the bike is made in Japan and they use metric
I know the US is slowly being dragged kicking and screaming into the 21st century when it comes to thread sizes, however I doubt they would get this so wrong
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Post by oldbritguy on Jun 23, 2020 21:03:25 GMT 1
Apologies Mark, I missed the point where you said you fitted one of Norbo’s pump gears at the beginning.
I think you will need to do a bit of maths on this one (or is it trigonometry? Lol).
I would first confirm which primary gears you have i.e. banshee and track down the profile of the gear teeth and ratio of the primary drive. Then the diameter and number of teeth on the crank gear then compare to standard sizes. Then you can look at the size of the gear for the pump and the teeth spacing and profile as well.
Not really different to matching final drive sprocket sizes. If the crank sprocket is bigger than standard then the pump gear will need to be smaller in diameter to prevent binding in the gears. If the other way about and the crank gear is smaller then the gears will not fully engage and slop about very noisily. The pump gear will need to be slightly larger in diameter to maintain the correct meshing. (Making sense so far?)
There must be a pump gear available for the banshee primary even Stateside.
If not then a good engineer should be able to make one for you based on how good your math is lol😆
Final option (expensive) would be purchasing a fully matching set from one of the sources you mentioned earlier.
Hope this makes some sense
John
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Post by shaunthe2nd on Jun 23, 2020 21:25:25 GMT 1
Makes sense to me on basis that the centre to centre distance between the meshing gears is fixed, so if one gets bigger, the other has to go smaller to ensure decent meshing.
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Post by Tobyjugs on Jun 23, 2020 21:40:07 GMT 1
What primary ratio were you using 2.36:1 2.68:1 or 2.86?
These are slightly different to the Nova 2.65 ratio and the gear wheel from Norbo will probably based on this spec and not the above.
I also have a set of 2.65:1 which uses another size of teeth and numbers to either Nova or Norbos Primary gears.
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Post by flames on Jun 23, 2020 21:46:49 GMT 1
That is a hell of a lot of damage in 3 minutes. You must have heard there was a problem? or have you got clear clutch cover conversion and see it?
Reason I ask is 3 minutes isn't very long for the damage, but would seem like a lifetime if you could hear it happening.
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Post by Tobyjugs on Jun 23, 2020 21:58:42 GMT 1
I forgot to say i have a set of Norbo's primaries in my 443 engine and they are so far so good. The only thing i noted was the gear teeth clearance was a little bigger compared to the Nova primary set.
My engine has run approximatly 40 minutes with two visual inspections. Cover off.
Total running hours on my engine is just over 1 hour.
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Post by 4l04ever on Jun 23, 2020 23:35:23 GMT 1
I would just run premix...
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Post by markg64 on Jun 24, 2020 0:23:36 GMT 1
That is a hell of a lot of damage in 3 minutes. You must have heard there was a problem? or have you got clear clutch cover conversion and see it? Reason I ask is 3 minutes isn't very long for the damage, but would seem like a lifetime if you could hear it happening. To be honest I couldn't hear anything when she started for the first time I was so pleased it was running. Had to turn it off to talk to my mate it was so loud thanks to the mark Dent pipes lol |
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Post by bare on Jun 25, 2020 3:54:23 GMT 1
Frankly surprising that .
Clearly someone's wits were left 'outside' somewhere during the assembly stage.
Small sympathies for sloth generated problems... TBH.
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