Hey guys,

finished the install of the 351 on my bike over the weekend. All went well and have now done ~80km's on the new engine, no problems. I video'ed the first start of the new engine, i was a bit worried when i first hit that starter something terrible would happen!


So far the change is amazing, the bike is 100% more rideable on the road (havent had it off road yet). Easier to ride because power is on tap and much easier to attain road speeds and scoot ahead of traffic.

If anyone is considering it I would definitely recommend it. The job was quite easy, took about 10 hours all up with a lot of fluffing about, if i was to repeat you could do it in half that or less.

Couple of questions from those who have gone before:

I re-jetted up 2 on the main (to a 132 dynojet) and left the pilot as the dealership gave me the wrong part. Not sure i need a larger pilot - can anyone comment on what I might experience if my pilot was undersized?? I note it is much harder to start, needs choke for at least 20-30seconds, before i only needed it for 5 seconds or less if at all. (I am in a warm climate at 0 elevation).

Anything to watch for that others have run into? All gaskets seem to be holding up well with no leaks, not sure what other issues may arise as it runs in.

Oil changes - i dumped the oil after 1 hour of riding, and intend to dump again in a short interval, say 1000km's. After that, just normal maintenance. Is this in line with everyones logic or has anyone got any other suggestions?

Thanks fellas.

 

I've gone smaller with big bores, not sayin you will too, but many times the increase in vacuum, the motor pulls sucks more fuel through a (same) size jet.

 

The pilot circuit will effect mostly the idle and 1/8-1/4 throttle performance. Harder starting will result if you are running lean on your pilot jetting. You can fine tune that with the pilot screw as well.

 

I'm in Ohio (~800ft above sea level where I ride) and I had the 38 pilot installed. Swapped it out two weeks ago for the stock 35 pilot and all it runs much better. You'll be able to tell if it's out of whack depending on starting times and if there is any decel popping coming to a stop. You might feel hesitation too.

132 on the main seems a little rich for right at sea level.

 

Stock Pilot is fine. Adjust the air-fuel screw a bit, if needed. 132 main IS a tad rich...I ran mine purposefully with a 132 while in the very hot desert. 128 is more appropriate for the conditions I run now. Oh, mine is a 331, not a 351, but, not much difference between the two. Don't bother changing your oil out early AGAIN. You aren't breaking in anything but rings...and they've already seated. Besides, oil filters get MORE efficient as they are run longer and longer.

Great job!

 

Richox, the harder starting may well be from the small starter jet that this carb comes with. Many of us have drilled the stock starter jet to overcome this. This is a fixed brass jet that supplies the fuel when you pull the choke **** open. Trying to address starting issues with a bigger pilot jet often causes on over rich condition when the bike is fully warmed up.

 

True story. A #38 pilot made my 250 start right up without a choke, but the soot built up quickly and mileage dropped. The drilled enrichment (choke) jet made a world of difference.

 

Depending on what intake and exhaust mods you have done a 132 may be just fine. I am at around 1000ft. Full exhaust, two snorkels, k&n and no screen and the 331 is happy with a 132. Just sayin not everyone has the same setup, elevation or climate. You have to find what is right for you.

 

Plus, there must be small variations between various bikes....put it all in the mixer and you have to find out what is right for your bike, just like you said. I'm not convinced a 128 is perfect for my bike, since about 5000 feet is as low as it's been run lately. If I have to take the carb off for some reason, I might try a 124 just to see...then again, I do plan to visit my old friends down in Death Valley every once in a while...in which case I'm sure I'd rather have the 128 in!

 

No Arguments from me on this. It was more general information on the pilot...

I don't think that turning the pilot screw is a bad idea however. You can go rich even with that however. I think the issue like IDRIDR had is a result of just doing too much of a good thing. On my Ninja 500 I was able to make it start like a dream with the pilot screw out 2.5 turns. It was soggy rich though below 3k on part throttle though. Backing it in until it was borderline bad starting without the choke gave good performance down low.

In general these bikes are designed to take a little choke. If you are starting great without it then you just may be (likely are) rich.