HI Justin, I have not had this problem running 4RT's since 2005 so I can't speak from experience. However high current draw is usually what burns out electrical appliances. This occurs from excessive load on the unit,or LOW voltage.
Low feed voltage increases the current draw (amps) . High voltage does not. Really high voltage can arc through the insulation or cause damage to electronics but not burn out wiring or motor windings.
So don't agree that 14V will cause the fan motor to melt.
If you have one and can mount it in the right way you can use a DTI dial or depth test indicator. With the dti resting on the rocker..engine on compression you can rock the rocker and get a reading. Space is minimal and it is fiddly. The most important thing is to re check the clearance after tightening the locking nut. Bending a normal feeler gauge is the easy way to go.
How can this work when both valves are opened by one rocker arm? Surely all you will measure is the tightest clearance? The other valve could be an excess clearance and you would not measure with a dial gauge?
In the UK a fastener threaded all the way was referred to as a "Set Scew" or 'Machine Screw" , Bolts always had a shank and a threaded section I believe to reduce the stress concentration around the head when subject to high torque and high tension loads.
I am around 62kg and have always found the Showa spring to be to strong and the damping to slow for me even when wound to full soft. Could not find a softer spring ready made (possible to have one made)
I went with a TRP rear shock with a 62kg spring back in 2006 and found the TRP perfect for me and has not required any service despite regular competition use.
I have just purchased a new aluminium body TRP for my 300RR, same excellent performance and approx 550gm lighter than the Showa and a reasonable price.
Hi Fred, on mine checked valve clearance when they became reluctant to start when hot (third or fourth kick not first kick). My 06 Repsol was after 54 trials (200 riding hours) and inlet were OK but exhaust were at the tight end of spec and immediate improvement in hot start after adjustment. My 2014 RR 260 was becoming difficult to start when hot and also very jerky motor response at low revs after 71 trials (logged as 314hrs.) On the '14 all valve clearances were at the tight end of the spec (i.e .03 under nominal value) but still just in the range given in the manual. Adjusted to the slack end of the range and an immediate significant improvement. I have to say the change in the 260 was not only in hot starting but the motor was so much smoother at the bottom end, it was like riding a different bike. My experience has been that the clearances are better set at the wide end of the quoted range and that they have remained stable for a long period after initial adjustment. It is a bit of a painful job getting to the tappets removing the injector etc. especially if some of the wiring connectors are reluctant to separate, they are hard to get hold of the connector body and I don't like to pull on the wiring loom -- no excuse but that is why I have not done them as regularly as maybe should. Good luck
Is it as simple as that ? I have heard it can lead to no start issues adjusting the idle ?
Yes it is that simple. It is good to use a tachometer to set at 1800 but if not available just adjust the idle screw a bit at a time whilst listening to the motor. If you go to slow and it doesn't want to start readily, just adjust a little back the other way, it is not that fancy. I think that it also depends a little on the programme that you are running, My older 250RR I ran a soft bottom end programme (Zogg3 from memory) and the bike performed reliably with idle set down at 1200 rpm
4t's run hotter than 2t's and you have to accept it.? I had the same concerns with my '17, the temps in Texas run near 100 f and the fan hardly ever shuts off. It really bothered me for a while but it is normal so I just ride and enjoy. Just FYI, my Beta 300 4t fan runs constantly after it warms up, perfectly normal. I had to accept that too.
That advice is correct however no one has asked if the fan is running while you are riding, if the fan does not run at least part of the time you have a fault and the motor will be hotter than normal leading to serious overheating.
I tried to find that spec too but no luck. Since you're tightening threads with oil on them into aluminum with a paper gasket I just went by feel and got them snug using the cross-cross pattern. I cleaned my bike after I was finished and just checked for any weeping oil while I rode for a while. It pains an engineer to not have a torque spec and just go by feel! ?
My manual does have a table of standard torque values to be used when not otherwise specified. 6mm is 10 N-m and 8mm is 22N-m
I was wondering if anyone has found a suitable replacement top bush for the Showa 39mm forks. I am gathering quite a collection of faulty bushes as each replacement one I buy fails in the same manner (teflon pealing off and getting under the seal). The last one I bought lasted just one month (3 rides) and I'm getting quite annoyed about having to replace the bush and seal this often.
I was hoping to find an aftermarket replacement or something off another bike. The dealer here has contacted the factory about this a number of times and they continue to deny the problem and just say it's not a warranty issue. I don't want warranty, I just want a bush that lasts like it should.
Some of my bushes:
Hi Chris, Exactly the same as my collection of bushes. I can add that after the first couple of failures I started orienting the bushes with the split to the front of fork leg, so that I could tell the position that the Teflon was peeling from. In my case it is the lower, rear section of the bushes. This eliminates any suggestion of the forks being out of line due to not centering the front axle. (In my case as noted in earlier post I have assembled front axle and fork bridge with the fork legs in full compressed position ) I too am convinced that it is a problem with the coating process because the damage does not extend vertically through the bush as would be caused by any fork tube damage. My dealer has sought advice from the factory but received no response, of the failures that I know of with the Showa forks all occurred after a short period from new and have continued following rebuilds, I have not had this on any of my previous Showa units.
Are the race tech bushes manufactured by them do you know?
I don't think the damage is mechanical from topping out, there are no marks on the edge of the bushing to indicate contact.
Whilst unlikely don't forget that tight valve clearance will also definitely affect ease of starting. It is generally preferable to set the valve clearance at the upper end of the book limit.
Hey guys does anyone know a tip to refitting a 4rt sump plate after a service. Not done it yet but worried if I take it off I won't be able to refit as I've read lots of nightmares about it.
thanks
Simon
I have used the same system since '05 and never had a problem and yes mine gets plenty bent. I just use a good G cramp, prior to removing the plate I slip the G cramp over the bash plate at the rear and tighten up onto the cross frame (you can't get exactly central but doesn't matter) then slacken the front mount bolts about 5mm and then the undo the rear bolts and remove. Slacken the clamp off and remove front bolts. To replace, reverse process. With the clamp removed, start the front bolts and screw in about 3-5mm, then lift the rear of the bash plate, slip the G Cramp over as before and then tighten the cramp until the plate is close enough to start the rear mounting screws. When all well started tighten all screws and remove clamp. Believe me it takes longer to type than to fit the plate!! my G cramp is a 6 inch clamp. The reason I use the clamp when removing the bash plate is that it is easy to rip the last couple of threads out of the frame if you just undo the screws when the bash plate is badly sprung.
Has anyone had any experience back bleeding a new bractec system? I believe that back bleeding is the best way to get a good solid feel at the lever but there is no way I can force the fluid back through the system.
Any help would be much appreciated
If you can't back bleed through the master cylinder check that the lever adjuster is not set tight, this will hold the master cylinder piston down in the bore and block off the return port. Just back the adjuster right off whilst back bleeding and it should flow straight through to the reservoir.
I purchased a used 06 Repsol 4RT to see how I got on with a 4 stroke and am now a complete convert.
Going through the various spares and bits in bags that came with the bike recently, I found 2 used sleeves with flanges that appear to have been previously fitted somewhere in the exhast system; according to the wonderfully concise manual, one of the sleeves looks like it fits inside the header pipe where it bolts onto the cylinder head and the other sleeve looks like it fits in the silencer socket which slips over the other end of the header pipe.
Are these items removed for any reason?
I do know that the diffuser on the back end of the silencer does make a difference to the noise if removed but probably does not affect performance but what about these other 2 items?
My 05 came with three restrictors in the exhaust system as you describe, the separate instruction leaflet accompanying the bike noted that they were for compliance reasons and should be removed for full power in competition set up. My dealer advised leaving the smaller diffuser at the end of the silencer to give max low speed torque.
Over here the 06 Repsol came without any of the compliance parts such as lights and restrictors etc.
Thanks for that really interesting information, particularly as there had been a previous post where most advice suggested the tensioner could not be a problem.
Just goes to show there is always something new to learn on the forum.
I'm going to be changing my oil's and fillter for the first time, and have all the info to carry out the work, except for the torque spec of the casing bolts.
would the bolts on the clutch side be the same Torque ( for future reference )
Thanks.
All bolts on 4RT not specifically covered in the manual use standard torque settings
5mm dia use 5NM 3.5lb/ft
6mm dia 10 NM, 7lb/ft
8mm dia 22NM 16lb/ft
Take care when replacing filter cover to push the cover fully home and square and hold it there as you fit the keeper and bolt and tighten. If you use the bolt to push the cover into the housing it will go off center and jam in the housing.
I have what I hope is a camchain tensioner in need of adjustment; the manual says nothing about this. It looks like it may be an automatic tensioner. I don't want to remove the cover and end up overtightening the chain.
Has anyone any experience of doing the tension?
Before removing the tensioner you should remove the pressure from the unit using the tool shown in the book and turning clockwise. Then remove tensioner unit and check spring tension, it is unusual to fail but possible for the spring to break. You cannot over tension the the chain provided the tensioner is not damaged.
That Clake setup is very interesting, relating to the MTB, rear brake lever on the handlebar has much more delicate control.
I do like the sound of a finger operated rear brake.
But...
What about the balance of clutch and brake?
I can understand it working nicely to stop endos, but what about control in...for example...slow full lock turns up and down a steep camber.
It is also very pricey!
Hi TB, I see you have the website link, I haven't checked lately but there was a good trials demo video on there with Matt Newlan.
I have used the unit for last 8 years and has been the best thing I have had on a trials bike. When correctly set up slow full lock turns etc are one of the main advantages of the unit, I find it much smoother than using the foot brake against the clutch.
If you would like more detailed feedback pm me and I will share my experience with you.
I have relatively small feet for a bloke, just size 8 boots.
I like to stand on the rear of the pegs.
(to weight the back of the bike for more grip and to lighten the front of what is supposedly a front heavy bike).
If I do, I can't reach the brake pedal, which means I have to have my feet further forward than I like, to use the rear brake.
I know there are shorter alloy brake pedals available (expensive ones at that), but I have read that they are tucked in.
I would hate to purchase one only to find that I then have to hug the frame with my boot to operate the pedal.
I like to stand towards the outside of the pegs for better manoeuvrability.
I have read that the Sherco pedal fits well and works better.
Is it shorter than standard but not tucked in like the alloy jobs?
What year / model Sherco one fits the 2015 4RT?
Any tips?
At the risk of attack from Nigel, I solved the problem completely using the Clake set up so rarely use the foot pedal.I have the dual control unit with the foot pedal retained. I have Raptor hangers and pegs that are about15mm further rearset from standard and tend to ride more on the balls of my feet, so works for me !!
I have extended hangers and pegs and stand fits fine. However it is still useless. I have been using Mitani alloy stand and VERy happy with that, out of the way of rocks, very stable and light.
Thanks for the info. I have also had 4RT's since 2005 without experiencing these bush problems, only normal wear after a couple of years, with the exception of one machine where it was necessary to replace fork tubes due to rock damage.
I would initially have guessed that the problem was caused by not centering the forks on the front axle at the factory causing binding on the fork bushes, however I have now replaced three sets of bushes with the Teflon peeling off and am most careful with correctly centering the axle before torquing up the pinch bolt.
In fact last rebuild I left the spring out so the forks were on full compression before tightening the pinch bolt. (and yes the axle is a free fit in the slider) The forks run freely over their full travel when the bike is lifted onto the stand.
I cant think that it is possible to bore the bush/seal housing in the slider off center from the main slide bore as you would expect these to be bored from a single machine set up, but theoretically this could give this damage pattern.
The fact that the Teflon is peeling off part of the bush and can be removed easily with a tooth brush suggests to me that the issue is the coating application. ( I also note a recent change in the part no. for this component)
Once the Teflon has gone there is no further problem with contamination or seal leaks, but I am not happy running the bare copper bush surface on the fork tube.
The fork tubes are expensive, but it is also expensive replacing bushes and oils every couple of trials.
ANYBODY any ideas?? Mr Sunter have you seen this issue in the UK?
It's to stop your fingers being cut off if you fall off the bike on to the rear wheel or someone tries to catch the bike.
It is not for guiding the chain, they are fitted to mx and enduro bikes.
Exactly, and over here ALL trials bikes are required to be fitted with them (and the gearbox sprocket under some circumstances. The Motorcycling Australia Rule book specifically lists them and checked every trial by the scrutineer. I am aware of two amputations from the rear sprocket, one at the SSDT a couple of years ago when the shark fin went missing during the trial.
Yes, Showa. My sons 2015 Repsol. I've got a 2011 and never had any problems
Thanks for the info. I have also had 4RT's since 2005 without experiencing these bush problems, only normal wear after a couple of years, with the exception of one machine where it was necessary to replace fork tubes due to rock damage.
I would initially have guessed that the problem was caused by not centering the forks on the front axle at the factory causing binding on the fork bushes, however I have now replaced three sets of bushes with the Teflon peeling off and am most careful with correctly centering the axle before torquing up the pinch bolt.
In fact last rebuild I left the spring out so the forks were on full compression before tightening the pinch bolt. (and yes the axle is a free fit in the slider) The forks run freely over their full travel when the bike is lifted onto the stand.
I cant think that it is possible to bore the bush/seal housing in the slider off center from the main slide bore as you would expect these to be bored from a single machine set up, but theoretically this could give this damage pattern.
The fact that the Teflon is peeling off part of the bush and can be removed easily with a tooth brush suggests to me that the issue is the coating application. ( I also note a recent change in the part no. for this component)
Once the Teflon has gone there is no further problem with contamination or seal leaks, but I am not happy running the bare copper bush surface on the fork tube.
The fork tubes are expensive, but it is also expensive replacing bushes and oils every couple of trials.
ANYBODY any ideas?? Mr Sunter have you seen this issue in the UK?
Unfortunately, the dealer(s) here in Australia claim not to have heard of any problem. They've obviously not heard of the internet either.
To each individual they will tell you that you are the only one to have had this problem (implying that it is your fault somehow). Clearly, there is a real problem with the Showa fork bushes from 2015 onwards. I say onwards because, as Oz Thumper says, the replacement bushes are failing as well.
Very disappointing.
Hi Chris, A little harsh, I have seen the correspondence between my dealer and the factory in regard to the bush problem. The factory is simply saying that there is no problem with the Showa forks in general and no problem with the bushes in particular.
Thanks for posting the photo, that is exactly how both my bushes were on my Repsol when first stripped. It is clear that there is an issue with the Showa forks and that it did not exist on the pre 2014 machines, the factory attitude is bloody annoying.
Mont 4RT Burning out cooling fan motors ? Why
in Montesa
Posted
HI Justin, I have not had this problem running 4RT's since 2005 so I can't speak from experience. However high current draw is usually what burns out electrical appliances. This occurs from excessive load on the unit,or LOW voltage.
Low feed voltage increases the current draw (amps) . High voltage does not. Really high voltage can arc through the insulation or cause damage to electronics but not burn out wiring or motor windings.
So don't agree that 14V will cause the fan motor to melt.
Good luck