Well it's good to hear that you've got 12k on yours with no issues! Makes me feel better ;D.

 

No i wasnt clear sorry i rushed the message. My 351 has around 4k miles on it. But a member at advrider has about 50k on his

 

kj, I'm not sure about your description on the use of first gear on a big/long hill climb. If you're in first gear and have the rpm at a fairly high level, you're very likely to bust the rear wheel loose. Yes, you often need first gear for a climb, but it's still a careful modulation of throttle to keep the rear wheel hooked up. Revving to redline in first gear will commonly result in the rear tire breaking loose on a climb...unless you're riding on a traction rich slickrock surface found in Utah and such. In many technical climbs with poor traction, I'm often in first gear to insure that I get to the top. In other cases where I can keep speed up, of course I stay in as high a gear as possible. Riding the bike in most off road situations at redline usually doesn't yield very good results unless traction is extremely good or a lot of speed is already achieved.

 

You are correct that better traction may be achieved with a higher gear, but my point was that , very occasionally, there will be situations where that ideal gear is impossible or nearly impossible to use because there is no way to build up enough speed at the base of the hill to make it work. In a case like that, revving out first to very high rpm may be the only way to initiate the hill climb at very low speed and yet still rapidly accumulate enough momentum to make up the rest of the hill. If you tried to use second gear in this example, you'd spooling up the rear wheel a bunch anyway due to having to manipulate the clutch, and you'd be having a hell of a time even.getting over the logs, big rocks or ruts, or whatever in the first place, if trying to do so in second gear at say, 5 mph. What I'm saying is second gear isn't always possible, even with big bore torque. And it will be nice to be able to rev the bike out to build a strong momentum enough to make the hill in those situations.

 

Plus we have to remember that, in the case of this particular motor at least, the motor actually makes less torque and horsepower at say, 9,000 rpm, than it does at like 6,000 rpm. So in theory id say you'd be less likely to get wheelspin at 9,500 rpm than at 7,500.

 

I think my entire idea here can be summed up by saying that, to me at least, being able to rev the motor higher will make my bike more versatile for extreme situations, more options/possibilities...lol. That's why I asked about safe engine rpm in the first place, just want to know what is possible with my machine. I'm used to doing a lot of hill climbs revving the living **** out of the motor on my dr200 for a lot of hills, because even if you have momentum, its second gear still doesn't pull for **** lol. All positive feedback is appreciated

 

I'm doing the 351 as I write but even in 250 form I have only bounced off the rev limiter once or twice in 6000 miles. Just no good reason to spin it that hard, it's time to shift.

 

im in the same boat as you, mate. i just got a 331 Bill Blue Kit installed as well but im afraid to take it to higher rpm. when i first got it, when the RPM reaches around 7000, i can feel a slight vibration down at the engine (like it feels tight), so i didnt dare go past 7000. Now that i have clocked slightly more than 1000 miles, the vibration is less but there is still a bit but i dare to take it to 8000 but not beyond that. i still maintain my rpm around 6000-7000 but occasionally bring it up to 8000. yesterday when riding it in the afternoon when the temperature was around 92F, when i the bike was moving slow or coming to a stop, the high temp light on the bike turned on. not sure if i should be worried about it. also, the oil level also drops a bit when i ride it, is this normal?

 

Yes, if you check the oil right after riding, it should read lower than if you check it after the bike has been sitting for a long time (like overnight). Just make sure that when the engine cold, the oil level is well within the bubble. The temp light to me would be a bit worrying to be honest. I don't think it should really come on during any kind of normal operation like that. I've had mine at a stop for 3 or 4 minutes, when the engine is hot, in 95+ degrees so far with no light, and I'm still running conventional oil for break in. As far as your temp light coming on, I would suggest a.) switch to synthetic oil (I personally Recommend Royal Purple Max Cycle synthetic) if you haven't already, and b.) use Engine Ice coolant in your radiator. When you change your coolant (to Engine Ice), make sure you pour the new coolant into the radiator SLOWLY, so that air doesn't get trapped in the system, as that can also cause heat buildup. Also don't forget to change the coolant in the reservoir as well. I would ask about your jetting but I'm guessing you have the fuel injected version - and I assume you're running the proper electronics/injector upgrades to work with the 331? Running Engine Ice in your radiator and Royal Purple in the engine should significantly reduce operating temperature. Also, as far as the safe RPM goes, I've come to the conclusion that 9,000 RPM is the "red line" of this motor. I came to this conclusion by listening to engine/exhaust noise and feeling how the power builds and then declines. It really seems to quite sharply decline from about 8,500 to 9,500. I generally always try to keep my motors a little below red line, except for a blast all the way up to it once in a while. So with my bike, I will keep it under 8,000 RPM whenever possible.

 

Thanks for your reply and recommendations, KJ. Actually i check the oil level when left over night and it still seems to have dropped slightly from the original level but still within the bubble. i actually had to add a bit more oil to get it at the original level again. My next oil change i will change it to semi-synthetic from mineral oil. When i installed the big bore, the shop put in Sikolene coolant which i thought should be quite reputable. however, i will monitor the temp light problem again, dont have time to ride it again since few days back.

Actually, i converted my fuel injection to the tm-33 carb because i wanted to fit the IMS tank but im not sure how to check the jetting, im not too good with mechanical stuff so the bike shop installed everything for me. can you advise on the jetting or other setting? i'll test ride the bike again this weekend and feedback.