ProMod Jackshaft chain alignment

Pit Bug

Pit Bug

New Member
#1
#1
Well since I couldn't find the thread I was posting on, I thought I would start fresh w/ this discussion of chain alignment w/ a jackshaft on a Doodlebug.

It seems w/ all the adjusting I have tried I just couldn't get enough slack out of the back w/o putting my tensioner in a different position and taking up the extreme slack.

I've been told to try a "half link", but haven't got one yet and don't know if that is a reliable part to put in a chain behind this much bigger than stock motor?

Right now I have it to where I can drive it fine, just don't know if the front chain is considered too tight ? And if the rear chain set up looks ridiculous and needs to be changed?

Some pics....


Front chain











Rear chain...








Rear chain w/ some tension removed...









* Pics for Buckeye since he can't read. :laugh:

.
 
Pit Bug

Pit Bug

New Member
#2
#2
I haven't tried any adjustment by moving the motor plate because the PMR plate I bought didn't fit the stock plate and I had to drill the stock plate to fit it and I didn't have a way to slot it at the time for movement. Bad design IMO
 
C

Camjamsdad

Active Member
#5
#5
Check the OldMiniBikes warehouse for premium chain. You'll need 2 boxes.

As far as the tensioner I removed mine since the chain is short off the jack shaft. Absolutely no problems. I'm even using the old wore out stock chain. You can pick up master links and half links at your lowes store or ace hardware
 
ProMod

ProMod

#6
#6
Pit Bug
The design of the PMR Motor Mount allows the plate to move forward and backward with more than enough adjustment for the rear chain tension, with or without a jackshaft system. (That is if you installed the mount as per our instruction sheet. ) The slotted holes in the Jackshaft plate are only for adjusting the primary chain tension . And should be done first. (some may not understand this and try to adjust the rear chain by moving the JS plate. But as you see this just makes one chain get tight while the other gets loose)
Anyway... after the JS mount bolts are tight the engine is moved forward or backward to adjust the rear chain. The rear chain can absolutely be adjusted without the use of a half link.
If the PMR Motor Mount instruction sheet was followed correctly you should have around 1.5 inches of travel forward and back to work with simply by loosening the four nuts on the bottom of the frame plate.
I also am available via phone or e-mail for any tech help.
Sales@promodraceparts.com
360-220-1290
Mini Bike Performance Parts, Baja Doodlebug, Dirtbug, DB30 and MB165 Performance
 
Pit Bug

Pit Bug

New Member
#7
#7
I have a New Doodlebug w/ a Predator motor, I don't have 1-1/2" of play w/ the mount. :laugh:

I think I "may" have 3/8" before hitting the rear loop. (I moved the loop as far as I could.)

I'm sure your instructions were great for a stock bike, but I changed so much that I had to just get things to "fit".

I'm not "insinuating" that there was anything wrong w/ any of the products I purchased from you, just trying to make things work w/ the set up I have. :thumbsup:
 
T

tardman

Member
#10
#10
Hey Pit Bug, If you get the good chain , you will have to get master links from them also. The ones from the hardware store don't fit. At least this has been my experience. Nice job on your D Bug:thumbsup:.
 
Stangrcr1

Stangrcr1

New Member
#12
#12
I would recommend the RLV 120 length chain as when I got the 106 chains, I had to steal a couple links from another chain to make enough to fit my bike. Ended up with I think 110 or so with my TAV, and with your jackshaft setup, I bet it would be similar.

Better to have too much than not enough.

You results may vary.
 
creia

creia

#14
#14
tardman said:
Hey Pit Bug, If you get the good chain , you will have to get master links from them also. The ones from the hardware store don't fit. At least this has been my experience. Nice job on your D Bug:thumbsup:.
Click to expand...
This is exactly correct. Half links work fine and hold up w/o any issues in our experience. You will NOT find half links available for the premium chain, however.
Michael
 
Stangrcr1

Stangrcr1

New Member
#15
#15
One other thing about the RLV chain. It says prestretched. Not. I had to make one adjustment after install and first ride, and it seems to be staying there now.
 
C

Camjamsdad

Active Member
#16
#16
What amazes me is the amount of stretch the cheap stock chain has. I started with the motor towards the rear. Ended up now taking links out twice and moving the motor the lengths of the slots each time.
 
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