Sprocket Alignment - Comet TAV2

SVTKen

New Member
#1
I added a Comet TAV2 to a Coleman CT200 EX and used the OldMiniBikes Warehouse Riser Plate. I mocked it up to check the sprocket alignment and they are off by 3/16”. (I used an adjustable bar for snowmobile clutches to check the alignment and I confirmed that it was straight.)

What is the preferred method for aligning the sprockets. I considered cutting the rear axle bushing on the brake side and lengthening the sprocket side but I don’t think the brake will attached properly to the frame with that much removed from the bushing. The other option I considered is drilling out the riv-nuts on the bottom of the riser plate to give some adjustment and using washers and nuts to attach the plate.
 

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SAS289

Well-Known Member
#4
That's way off. Makes me question the quality/workmanship of the riser. A straight up and forward riser shouldn't create what you have. Another member here had this same issue on a 200U but I don't recall if he ever posted his fix.

I don't know for sure what the issue is there but Coleman frames shouldn't be trusted. Both of my 200U's have an identical frame issue but unrelated to what you have there.

I didn't have any alignment issues after chopping off the chain guard bar and making 1" risers for my bikes. This is why I would be looking at the riser plate first.
 

SVTKen

New Member
#5
That's way off. Makes me question the quality/workmanship of the riser. A straight up and forward riser shouldn't create what you have. Another member here had this same issue on a 200U but I don't recall if he ever posted his fix.

I don't know for sure what the issue is there but Coleman frames shouldn't be trusted. Both of my 200U's have an identical frame issue but unrelated to what you have there.

I didn't have any alignment issues after chopping off the chain guard bar and making 1" risers for my bikes. This is why I would be looking at the riser plate first.
I’m going to take some measurements and see if I can find what’s causing the misalignment, I’ll post what I find.

Just curious what frame issues you had, I returned the first one that I bought due to a bad welding job.
 

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SVTKen

New Member
#7
Maybe you can shim the TAV.
That’s something that I initially gave some thought to but it would cause other issues. The shaft on the driven sheave isn’t long enough to allow for shimming the sprocket over. The other option would be to make a shim plate to go between the motor and TAV backing plate. But in both cases it would would also cause other problems with sheave alignment.
 

SVTKen

New Member
#8
First off the motor riser pretty much just raises the motor without any appreciable side to side movement.

I did some measuring and included a scale in the photos for reference. It seems that the factory sprocket on the Coleman bike is 7/8” offset from the motor side of the the plate. The Comet sprocket is 1/2” offset from the motor side of the plate. This is where the issue is coming from. It’s too bad the top of the riser plates weren’t slotted for side to side movement. I wonder how many people have put these on not realizing how far out they are on this particular application.
 

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#9
I'm pretty sure there once was a thread with someone complaining about how bad that riser was. I think that thread was deleted, it was back when this forum and that warehouse place were under the same ownership, which would explain why it may have been deleted. I think I remember someone saying their riser was crooked on the baseplate and they cut it apart and rewelded it.
 
#10
I'm pretty sure there once was a thread with someone complaining about how bad that riser was. I think that thread was deleted, it was back when this forum and that warehouse place were under the same ownership, which would explain why it may have been deleted. I think I remember someone saying their riser was crooked on the baseplate and they cut it apart and rewelded it.
The riser plate is pretty close, but it should have slotted holes on the top to allow for the difference between the stock Coleman sprocket location and the Comet sprocket location. It would be an easy fix if the riser didn’t have the pressed in riv-nuts.
 
#11
I would but they are all ready slotted lengthwise for chain adjustment. I could widen the slots, I’ll add that to my options list.
I didn't know the plate was slotted, I assumed they used a chain tensioner like my CT100Us. I think your best option would be to slot the baseplate of the riser: Remove the inserts, plug weld the holes and grind flush, align everything, mark the drill locations from below, drill new holes and (optionally) slot them transversely for side to side adjustment.
 
#13
That might be the simplest solution. If you do that, I would suggest using some thick fender washers (washers with an extra large OD) underneath.
I’m kinda leaning toward drilling the riv-nuts out of the top plate of the riser. Then when the alignment is set I can adjust the chain tension without having to mess with the offset. Not sure if I’d weld and redrill the holes or just use fender washers as you suggested, guess it will depend on how large of a hole is left when the riv-nut is removed.

I’m considering emailing OldMiniBikes Warehouse, tell them what the issue is and ask if they have any riser plates without the riv-nuts. I’m doubtful that it would get me anywhere though.
 
#14
Go Power Sports as well as many other suppliers sell a thick aluminum plate
that has four slots for and aft, that bolts to your bike, and four other slots that give you about 1&1/2" side to side movement that the engine is bolted to. I have used on two different go karts to solve exact problem you are having. Well worth the money and takes care of the welding - slotting issue
right now.
 
#16
Go Power Sports as well as many other suppliers sell a thick aluminum plate
that has four slots for and aft, that bolts to your bike, and four other slots that give you about 1&1/2" side to side movement that the engine is bolted to. I have used on two different go karts to solve exact problem you are having. Well worth the money and takes care of the welding - slotting issue
right now.
I like the idea and the adjustability but the plates are 1/2” thick and I’m pretty sure you need to raise the motor 1” for the TAV installation.
 

SAS289

Well-Known Member
#17
I’m going to take some measurements and see if I can find what’s causing the misalignment, I’ll post what I find.

Just curious what frame issues you had, I returned the first one that I bought due to a bad welding job.
What I found is that the axle cannot be set up equal in the slots. If the wheel/axle is as far froward in the slots as it can go the sprocket will not line up properly. The brake side of the axle needs to be adjusted further back than the sprocket side. Easy to see engine off the bike with a straight edge on the sprocket using the engine plate as a reference. And it's not just my 2 bikes. I mentioned this to a guy on youtube and he found the same on his 200U. It's not a big deal and just a matter of knowing how much more adjustment is needed on the brake side.
 
#18
I'm dealing with same problem on a new MB200S. Except mine is out close to 5/8". So they're sending me new frame. I have the same riser with the threaded inserts and I did not like the idea of cutting slots in it either. You are correct in needing at least 1" of rise for TAV. So if what SAS289 suggested is not enough adjustment, you could mount that adjustable plate to riser, that would give you around 1 5/8" rise and I don't think that would be an issue.
 
#19
I'm dealing with same problem on a new MB200S. Except mine is out close to 5/8". So they're sending me new frame. I have the same riser with the threaded inserts and I did not like the idea of cutting slots in it either. You are correct in needing at least 1" of rise for TAV. So if what SAS289 suggested is not enough adjustment, you could mount that adjustable plate to riser, that would give you around 1 5/8" rise and I don't think that would be an issue.

Just out of curiosity measure the sprocket offset on your original gear reduction plate. I’m measuring from the back of the plate to the inside of the sprocket and it’s 7/8” versus the Comet TAV which is 1/2”.

I bet there are a lot of people with alignment issues if they just trusted that raising the motor positions it correctly.
 

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#20
I looked at same thing you are, I have the jackshaft on my CT now that the TAV came off of and it aligns perfectly. When I put either on the new frame they are both off by around 7/8" yet the jackshaft drive gear appears and does measure out further than the TAV. But they are actually on the same alignment. Do you have an alignment issue with your jackshaft with engine mounted to riser ? If not then I would be looking at a prob with the TAV back plate. Using a riser in no way affects the alignment, other than raising the geometry. Unless you have a messed up riser. I would start testing all of it with a straight edge. If there was a big issue using these risers with a TAV, then we would of heard about it. I'm on multiple FB pages dealing with minis and here. I've personally helped numerous new owners, by suggesting that riser and a TAV, with no alignment issues. I can't imagine that your particular model mini should be any different. One thing for sure, the QC on these minis and upgrades is very lacking !!!
 
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