Hiya all,  I've taken two springs out of my 4rt clutch and put dimpled plates in which has given a lovely clutch but slips in high gears. I am looking for a heavier duty spring to replace two of the existing 4 springs with to stop it slipping.  Problem is that the 4rt ones are 27.6mm long and the uprated 315 ones are 39mm.  Anyone know of where to get hold of 27mm uprated springs? 

Have you tried all the original springs back in with the new plates.

What year bike have you?

Cant quite remember set up but can you put washers on the bolts to allow them to be tight but with less compression.

I run std plates / std springs / atf oil on a 2015 and clutch seems fine to me. 

Thanks for the comment. The clutch is much lighter and gives better feeling- less switch like with the two spring removed. The washers idea is good. My bike is 06. Whilst I like the clutch for sections I'm not sure if the bike will be ok on road  for a 2day trial. 

Edited February 22, 20179 yr by Jeff mc
Extra info

Thanks for the comment. The clutch is much lighter and gives better feeling- less switch like with the two spring removed. The washers idea is good. 

Have you the original friction plates in as later bikes have got better. Also earlier bikes had smaller master Cyl - the 315 mont master cyl was a good mod to make clutch better on earlier bikes without the risk of the clutch slipping

The 300RR uses washers under the springs to get a little more preload and clamping force. If you want to see the location of the washers, there's a 300RR parts list on http://www.montesa4rt.nl/ and the washer is Reference # 20 and P.N. 22403-NN4-L60.

Mitani sells Tomoyuki Ogawa springs which are advertised as "stronger", Banyeres sells them.

Another option would be slightly softer springs and use all six. I can't suggest what would work.

Like JimmyL said, the newer friction plates are better. I use those with dimpled steel plates and Dex VI ATF, this works very well for me.

Edited February 23, 20179 yr by sportsawyer

I haven't been inside my 09 to see what previous owners might have done but assume it has a full complement of springs and original plates (which I believe are different from some earlier models).

Clutch is lighter than my Beta was and whilst my stock of Silkolene caused a bit of drag now I am on Rock Oil the clutch has the lovely action it did when I bought the bike over 18 months ago.

Hope that may help.

Edited February 23, 20179 yr by 2stroke4stroke

I too took 2 springs out after being on a gasgas for a few years as I found the 4RT clutch far too 'switch' like.

I gave Flexisprings , kingswood, Bristol a call - they have a range of 'stock' springs and I found a spec that would be close to the original dia but slightly shorter in length (a washer may be needed under the spring?) but a set of 6off 'new springs' would be equivalent in compression force to 5off springs (or close too) of the original set of 6off. If I can find the details on the email I will post it on here but if not you can drop them a line with the spring dimension's,-  dia, length, number of full coils and the wire dia and they will give you the spring rate. from that you can choose from their range of stock springs....from memory I think a set of 6off were around the £20 mark (minimum order charge)

In the end I left it with the two springs out as I only ride in the woods and rarely get out of 2nd gear so I didn't notice any clutch slip....

would be interesting to see how you get on if you do use their springs....

Why not replace the 2 missing springs with lower rated ones ?

Loads of great info here fellas. Thanks very much- really appreciate your efforts.  The mont 315 master cylinder I had heard of before but I think I'm going to try a washer on each spring to start with. I'm running basic silkolene light gear oil at the moment which may not be the best for the clutch but is hopefully going to look after the gear bearings. The ability to order specific springs for £20 sounds tailor made. That's my second best plan. I'll let you know how I get on. 

 

Jeff

Flexosprings is definately the place to buy springs.  

Jeff, did you new get new springs?

no.  They wanted £140 for the four springs.  I hadn't banked on that.  Rode today and it slips in 4th and 5th but nothing that steady throttle movement won't deal with. 

that much? was that for 'made to measure' ones or from their stock springs?

Yes made to measure. I couldn't find any off the shelf ones which are close enough to the free and compressed length.