frontroomautos Posted August 22, 2007 Report Share Posted August 22, 2007 I have posted this question in the Montesa forum also so i have posted here also so as to get balanced opinion. Sorry Andy i dont usually repeat in Forums. Can anyone tell me how many RPM's the 4RT revs to & how often it needs rebuilding. I am thinking of buying either an 08 Beta Rev 3 270 (so long as the stator problem is no more, ive been told its now sorted since enquiring) or a Montesa 4RT. I like the 4RT better but with its more complicated engine i am wondering about how often it will need a new top end and the comparative cost against the 2 stroker. My theory says that a low reving 2 stroke engine has got to be roughly about as reliable as a high reving 4 stroke engine & when it does need rebuilding it is allot cheaper. I havnt heard of a 4RT going bang other than at championship level but someone here might have experience of it and the cost. I would like to hear some knoweledgable experience sand advise. These questions are basically to assist me in getting nearer to a buying decision at the end of this year. I am just as undecided today as i have been a few months back about which to go with in 08 & I am one of these people who likes to iron out and eliminate questions before i take the plunge to buy. Cheers. Quote Link to comment Share on other sites More sharing options...
motojojo Posted August 23, 2007 Report Share Posted August 23, 2007 I don't have a 4rt but I've rebuilt several 4 strokes and the top end is not any more expensive you just need to know what your doing with the 4 stroke vs the 2 stroke. I would also say the 4 stroke will need less repair. Quote Link to comment Share on other sites More sharing options...
frontroomautos Posted August 23, 2007 Author Report Share Posted August 23, 2007 What 4 strokes have you rebuilt. Yes i agree that its a bit more involved but timing them up is not that hard. I could do that but of course the replacement of valves & springs and the other obvious things like rebore i would hand to the shop due to not really having the tools or know how, well replacing valves i could do but not the rebore. Its just that i heard it was more expense and i was a little concerned at the cost of replacment cost of EFI parts. A bloke at a trial i was at last month said he had a problem with this and his bike was in the shop at the moment. Quote Link to comment Share on other sites More sharing options...
amiller Posted August 23, 2007 Report Share Posted August 23, 2007 The top end of the 4rt is absolutely more expensive to rebuild do to valves, cam, ect. The 4rt is not a higher reving engine than the 2 strokes. Dependes who is riding them how much any get reved anyway. My Beta sees the high end of the revs quite often do to section difficualty and terrian. A novice rider may never see many revs unless by accident. A beta will go several years of hard use with no noticeable power loss as long as it has been well maintained, (airfilter, exhaust packing, good oil). If you want to freshen it up its a couple gaskets, piston and rings. No matter how you cut it the job is more extensive with the 4rt. Aaron Quote Link to comment Share on other sites More sharing options...
d. sileo Posted August 23, 2007 Report Share Posted August 23, 2007 Must agree with AMILLER, I have actually rebuilt a few top end on 4RT's....Double and triple the cost in most cases vs. a two stroke top end rebuild.....Expensive Quote Link to comment Share on other sites More sharing options...
frontroomautos Posted August 23, 2007 Author Report Share Posted August 23, 2007 Ithought as much its good to hear it from someone who has done it. How long could i own the Beta without any rebuilding work, I am what i would describe as quite an experienced novice if that makes any sense, I dont do splatters but dont shy away from high climbs and the usual medium hard obstacles. I intend to enter more trials in a more committed way when i get my new bike but until now i just practice. Quote Link to comment Share on other sites More sharing options...
amiller Posted August 23, 2007 Report Share Posted August 23, 2007 At your level with good maintaince, airfilter changes often, tranny oil changes often with a good fully synthetic gear oil, not atf, and exhaust repacking, you will not notice any loss of power over the next 6 seasons, maybe ever. I rode my 01 a while back that has been through 4 other owners since me and with a few adjustments I would ride it in Expert class right now. You will however want to rev it out occasionally. I find that with the sections you will normally be on the bike will load up a bit after a lot of slow lugging around. Kick here up to 3rd, hold the clutch and brakes on, rev her up and then drop the clutch a few times with the brakes locked to bring her back down quick. She should rev clean right up to the top all the time. Aaron Quote Link to comment Share on other sites More sharing options...
frontroomautos Posted August 23, 2007 Author Report Share Posted August 23, 2007 How do you mean 'load up'? Quote Link to comment Share on other sites More sharing options...
d. sileo Posted August 23, 2007 Report Share Posted August 23, 2007 How do you mean 'load up'? Listen to AMILLER.....Buy the 2008 Beta REV 3 , plenty of fun factor without the expense of costly 4 Stroke repairs.... Quote Link to comment Share on other sites More sharing options...
amiller Posted August 23, 2007 Report Share Posted August 23, 2007 (edited) The bike will start to run "fat" like it is overjetted. When you run the reves up the bike will not rev out cleanly up to max RPM. They motor will go flat and not rev to max. A good run down the loop or a hill climb or just a quick ripp on the throttle every once in a while will keep things perfect. I only point this out due to many of the novice ridders here have 270s and never use any throttle. The bikes will lug through almost anything so most riders never really crack the throttle open. Oh ya, my experience over the last 8 Rev 3s has been they like high octane gas. Hey Dom, are you coming to our vintage in Warsaw this weekend? Gate trials, wicked fun, food afterwords. Aaron Edited August 23, 2007 by AMiller Quote Link to comment Share on other sites More sharing options...
frontroomautos Posted August 24, 2007 Author Report Share Posted August 24, 2007 will super unleaded be high octain enough for it to run at its optimum? Quote Link to comment Share on other sites More sharing options...
amiller Posted August 24, 2007 Report Share Posted August 24, 2007 will super unleaded be high octain enough for it to run at its optimum? Should be fine. I like 110oct. with Ipone or ELF at 1.5 oz. per gallon. Not looking to start the great gas debate here that just what has worked very well for me over the last 8 years of Beta. Aaron Quote Link to comment Share on other sites More sharing options...
the addict Posted August 24, 2007 Report Share Posted August 24, 2007 Aarons right, Betas love high Octane fuel, get some AvGas in them 50/50 and they run sweet havent noticed much change though in the Sherco from normal super unleaded to AvGas so will stick with the pump stuff. Quote Link to comment Share on other sites More sharing options...
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