erikmaurer Posted March 4 Report Share Posted March 4 I have always owned GasGas 2 stoke trials bikes and am now considering a Beta Evo 4 stroke. Are the 4 strokes a pain in the rear for maintaince? The gasser 2 strokes rarely gave me trouble. Does anyone know if the betas valves or timing need a lot of maintaince or are they usually reliable without a lot of fuss. Any input would be appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
markparrish Posted March 4 Report Share Posted March 4 Well, I have owned a 250 4T version (2010) for about 4 years and maybe it's not typical, but I have never had to adjust the valves. I just change the oil and filter regularly and it just keeps running very nicely. I did feel concerned that I should be checking the valve clearances after owning it for a couple of years so I did, and they were spot on so I leave them alone now! I guess I'll be able to tell if they do need adjustment from a sound change or maybe drop in performance? My friend has a 4T 300 and he seems to have the same approach - and his runs sweetly too. They are lovely bikes, although you may find they ride softer than your two stroke (that suits my style of riding though). 1 1 Quote Link to comment Share on other sites More sharing options...
lemur Posted March 4 Report Share Posted March 4 I rode Montesa 4RT for years and find them easy to work on if you can just replace parts you smash on rocks and occasionally adjust valve clearances good. Friends that own the Beta 4-stroke have a lot more problem with starting the engine cold or after a tumble, the Beta carburetor is a down side when compared to the Montesa PGM-Fi You set the valve clearances when the bike becomes hard to start and you have ruled out everything else. Beta 4T handles nicely, slightly more lively then the Montesa chassis, but the engine performance really would improve with the addition of fuel injection. 1 Quote Link to comment Share on other sites More sharing options...
timdog Posted March 4 Report Share Posted March 4 Ive had 3 4ts and never had one bit of trouble. Never needed to adjust valve clearance or clean carb. Service/oil change is easy and i always found them easy to start, hot or cold. If you like a fast throttle stick with the standard or replace with an amal 80/200. Really softens throttle response. Cam on carb has 2 holes just need to put the cable nipple in the one that puts the cam at its biggest diameter(rear one) The low tractable power/torque is great, just pulls and pulls Factory model has better brakes and suspension. 1 Quote Link to comment Share on other sites More sharing options...
lemur Posted March 5 Report Share Posted March 5 All of my Honda engines had about 6 or 7 years of heavy use on them before the valves needed slack adjusting. It would be no surprise if a 9 year old Beta 4T is due for valve clearance attention, ymmv. A compression test 'might' be an indicator of valve clearance problems, but only if you have compression test results from when the engine was new to compare with. Carburetors and modern pump fuel with the corn alcohol added is a problem because carburetors have a vented float bowl where fuel can evaporate and leave behind residue or promote the growth of organic materials, by contrast fuel injection is a closed loop pressurized system other then the fuel tank itself so 'if' you never needed to clean and service a carburetor after running and storing modern pump gas in the carburetor, that would be absolutely amazing. Quote Link to comment Share on other sites More sharing options...
mcman56 Posted March 5 Report Share Posted March 5 I have a 16 Beta 300 4t and have been checking valves every 50 hours but they never seem to change so plan to stop. It is a lot of work to get to the valves. Everything comes off the motor except the swing arm bolt and the engine then rotates down around the bolt to get valve access. It is also quite a bit more work to get to the carb compared to the 2t. It is the quietest bike and easy to kick. 1 Quote Link to comment Share on other sites More sharing options...
lemur Posted March 5 Report Share Posted March 5 Holy 50 hours is far off the 6 or 7 year failure interval that I have been seeing, even on Honda generators. We are only talking about adjusting out the amount of metal fatigue and deformation in the valve seat here. The Montesa engine has a decompressor on the cam that is dependent on the clearance adjustment being spot on, I just checked a Beta 4T manual and the Beta 4T has a similar decompressor mechanism on the camshaft. Quote Link to comment Share on other sites More sharing options...
mcman56 Posted March 6 Report Share Posted March 6 I stand corrected. The number is 60 hours and came from an ISDT preparation manual put out by Lampkins. I was just following that recommendation but the clearance never seems to change. There was no failure. Quote Link to comment Share on other sites More sharing options...
erikmaurer Posted March 7 Author Report Share Posted March 7 On 3/4/2024 at 4:52 AM, lemur said: I rode Montesa 4RT for years and find them easy to work on if you can just replace parts you smash on rocks and occasionally adjust valve clearances good. Friends that own the Beta 4-stroke have a lot more problem with starting the engine cold or after a tumble, the Beta carburetor is a down side when compared to the Montesa PGM-Fi You set the valve clearances when the bike becomes hard to start and you have ruled out everything else. Beta 4T handles nicely, slightly more lively then the Montesa chassis, but the engine performance really would improve with the addition of fuel injection. you wouldnt happen to know the average weight of the bike? Im having a hard time finding that online. Quote Link to comment Share on other sites More sharing options...
erikmaurer Posted March 7 Author Report Share Posted March 7 22 hours ago, mcman56 said: I stand corrected. The number is 60 hours and came from an ISDT preparation manual put out by Lampkins. I was just following that recommendation but the clearance never seems to change. There was no failure. do you know the average weight of the bike? Quote Link to comment Share on other sites More sharing options...
mcman56 Posted March 7 Report Share Posted March 7 This claims 155 lbs dry. IIRC, the beta 4t is about 7 1/2 pounds heavier than the 2t models. The Honda is then another 7 1/2 pounds heavier than the Beta 4t. https://www.outdoordepot.biz/Motorcycles-Beta-EVO-300-4-Stroke-2024-South-Fork-CO-cfe3b8b3-3612-42bc-b1b1-b081007ec67e This says 170 lbs wet for the Honda. https://www.dirtrider.com/dirt-bikes/montesa-honda-trials-motorcycles-2023/ Quote Link to comment Share on other sites More sharing options...
jonnyc21 Posted March 7 Report Share Posted March 7 My 2017 300 RR Montesa came in at 164-165 and my 2007 4RT was 166-167 fully fueled and ready to ride if I am remembering correctly. Hope that helps. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.