thall1

I'm not a road rider, I just mess around on a trials bikes so my experience is limited, but as the question was asked by the OP & I thought I'd share my experience and thoughts.. I will never notice the difference between a carb and FI in terms of performance and I would respectfully suggest nor would most other clubman rider...FI is brilliant when it works and I'm sure somewhere in that black box its been programmed to give the best performance.. It appears many manufactures are now going to FI, but I suspect that's more to meet emission regs rather solely to provide the best performance for the club rider. In my experience, when it starts to play up its a pain to diagnose the issue without a second bike to swop parts and if your unfortunate to have an issue its not going to be a cheap fix. When trying to sort mine, most of the loom was corroded, Black wire corrosion all through the earths, most of the loom was replaced. When the ecu was opened up just before launching it into the nearest bin there wasn't any visible issues with it. I agree there are a number of elements within the carb that could effect its operation, but other than a blocked jet due to stale fuel or a bit of debris they rarely go wrong, just like a the FI system in 99%of bikes, but carbs can be easily stripped and cleaned ready to go again whereas a FI system can't...The other issue we found is the idle speed on the Montesa.. its around 1800rpm, any less and the bike wont start, whereas the beta is around 900rpm and it drops lower and still pulls whereas the Montesa will stall and we found we had to use much more clutch which was also relatively switch-like compared to the beta...just my thoughts and experience...

Riding a 4T is totally different but great. We've had 4t's for probably 11/12 years... did recently by a TRS just to see if we could be tempted back from the dark side but although the TRS is light and nimble I think we'll stick with the 4T's. You could consider the beta 4t. less complicated. No F.I, ECU, Throttle body, no expensive pump in the tank. Slower idle speed (4RT idles at 1800rpm). I'm a rubbish rider, but had a 4rt which I nearly scrapped due to intermittent throttle body issues. Got it fixed then moved onto Beta 4t's... never regretted it, so much so my son bought one. Had them for probably 8 /9 years now.. 4Rt's are lovely bikes but if they do go wrong (not often, granted) then its a pain to try and trouble shoot unless you have a spare bike to swap parts over on as I found.

thanks.. i had that issue when i first bought the bike...i ran it with a fuel tap for 5/6 yrs before getting a new soleniod

Update… found the issue…. A Pin on a waterproof plug had snapped internally… it was being held in place by the grommet in the back of the plug which made it seem it was in place but in reality it was being pushed out when the connection was made

Recently my bike overheated due to the fan not working.. fitted a new regulator and all was good. bike hasn’t been used due to gearbox strip down but now all rebuilt. bike ran at home with no issues in either the engine/ gearbox or the fan. Took it out Saturday and had intermittent fan for a few minutes then I lost all 12v on the bike again?… the bike starts and runs fine with fuel solenoid on the manual position .. fan will spin with a separate 12v battery connected. The regulator has five wires on the plug… black (earth).. two yellow from the stator and two blue which I assume is 12 volts output. what should I be seeing on the input to the regulator i.e on the two yellow wires?

They all look good… there is just the faintest sign that the blackened surface finish is wearing on the shift forks… the guide disks are also unmarked… I’ve been trying to see which part of the shift drum is used on what gears to see if the wear marks are consistent with the lower gears and probably neutral but it’s tricky to see. I’m assuming they are as the bike rarely gets used in anything above 2nd and all other guides in the drum are unmarked

Dummy built back up albeit not loctited… ( still need to order the rebuild parts) all I’ve done is very gently clean up the marks on the shift drum with 800 grit… tricky trying to hold everything in place whilst spinning the mainshaft and changing gear but it seems to ok?… I’ll try again when I get another pair of hands here to help me..

Yes I was going to replace the bearing as a matter of course… not sure this could be the cause of the issue?… any thoughts on the wear marks on the selector drum?… not sure these would be enough to jam the mechanism.. they look worse than you can feel

Had a good look over everything today… the only issue I can see or find are very slight wear marks on the crowns of the gear selector drum guides, and a very slightly notchy drum bearing… other than that it all looks to be fine… I’ll try and post pictures of the drum but I wasn’t allowed last time… if I do get them posted if anyone has any opinions on wether this would be enough to stop the gears selecting I’d be greatfil to hear your thoughts?

Thanks guys…. I’ll take another good look at it all tomorrow with fresh eyes!

That’s my next plan… the shafts are fine and they don’t bind on them.. I was going to put the shafts into vee blocks and check the squareness of the selector forks. Initial inspection shows nothing up..

Yes that was my first thought that it had snapped again but it’s fine hence why I’ve now stripped the gearbox

Just to add… the gear selector drum is virtually unmarked… and the pin the locates it in relation the the ident cam is also unmarked.

Yes, I did snap the paw from the gear selector shaft. I welded it back together, making sure it was exactly the same position from when it snapped, also made a new paw slide pin as mine had quite a bit of wear, you could move the lever quite a few degrees before it actually started to turn the gear cam. Gear change was brilliant after… I could select every gear with ease, even found neutral with the engine running! ( I can’t upload a photo atm… file to big-don’t know why?… perhaps I’ve exceeded my allowance?) everything was great until the bike went down on its left side onto rocks. After that I had a lever that didn’t really do anything but unlike when I snapped the paw assembly off the shaft and the shaft would just move excessively up or down as far as the bash plate, it didn’t seem to have full movement… after quite a few tries I got 2nd and left it there…. At first I assumed I’d snapped the shaft again or something related to it …There were no strange noises or anything to suspect gears were eating themselves.. and no signs of that now it’s apart… my son rode the bike for a while and he too couldn’t find anything bar 2nd. He got neutral a few times. and yes I’m spinning the shafts while trying to change gear using the indent cam. im at a loss now!?

So casings split… nothing obvious that’s broken or damaged. Using an Allen wrench on the gear change drum on the clutch side I can get 1st, neutral and 2nd… and there it stops? always had a problem when going 2nd-3rd it felt like 2nd hadn’t fully disengaged but cleared if I went back to 2nd the up into 3rd… lovely & clean inside.. no debris or any sort to be found which in some respects is very good but was hopping to see something obvious and maybe something sat in the bottom of the casing! any thoughts would be greatly appreciated!