70's 123 cota into 200 frame

[Twinshockandy]

Anyone know if the motor of early 123/172 cota (red one) will fit into later 200 frame ?

 

Am running a 123 with 400x18 rear tyre, and clearance in swing area isn't good to all.........easiest way would be to find a 172 swing arm, but they seem like hens teeth in the uk

 

I'm aware exhaust/silencer is different on the 200 cota

[section swept]

I suspect that the mountings of the two engines will be slightly different. You need a Montesa expert, I am not, but it does seem to me that you may well be going about sorting the rear wheel clearance the wrong way. Of course if you are not bothered about originality then crack on. If the wheel is moved as far back as possible does this improve the clearance issue, if so some longer rear wheel mounting lugs could be the answer. You can obtain these from a number of trials parts shops, or make them your self...not too difficult. This might slow the steering a tad but if it lets you keep the wider tyre all well and good. Is the narrower rear tyre unsuitable for your riding style, a narrower tyre will let a bit more power out if you get my drift. ?

[Twinshockandy]

8 hours ago, section swept said:

I suspect that the mountings of the two engines will be slightly different. You need a Montesa expert, I am not, but it does seem to me that you may well be going about sorting the rear wheel clearance the wrong way. Of course if you are not bothered about originality then crack on. If the wheel is moved as far back as possible does this improve the clearance issue, if so some longer rear wheel mounting lugs could be the answer. You can obtain these from a number of trials parts shops, or make them your self...not too difficult. This might slow the steering a tad but if it lets you keep the wider tyre all well and good. Is the narrower rear tyre unsuitable for your riding style, a narrower tyre will let a bit more power out if you get my drift. ?

Thanks for your thoughts section swept

On the 123 cota it when new it came running 20" front and 17" rear , which seems to be near impossible to find, certainly in the uk................(same as 172 cota swing arm, which would allow and give room for 18" tyre/rim.

Wheel, at present is right back in s/arm, as per your idea, but tyre (at present am running 400x18) still rubs on chain guard, and very close to swing arm pivot.

My other thought is going down to a3.50 x18 section tyre, (only found one distributor of these in uk) which will give slightly more clearance

 

Have also posted question in Montesa forum