Hawk tune up, top speed, and general musings.

[Megadan]

The TT250 and the Hawk both use 5.5mm valve stems vs. the 6.5mm. The valve springs are a double spring variety, but each spring is actually fairly light weight. At or just past 9000rpm they will start to experience valve float. You can try to shim them to increase preload and help combat the float a little bit, this is what CCW did with their land speed bike. Ideally, I would want different springs, but nobody offers anything off the shelf. You could likely match up springs of the right diameters and heights that would work, but you would need to known the spring rates of the stock springs first. Then you have to get past the limitations of the cam profile, which as Jerry said, isn't very good for spinning past 8500 anyway.

[Wild Dog]

Originally Posted by OneLeggedRider

Perhaps I was a little rude with him when I commented on doing something useful, but I just get tired of him plugging his wares on posts that aren't relevant. I definitely don't need a first tune kit and I was joking about starting over with the Mikuni clone. And I think some of his kits are a definite value, but just ease up on spamming every post.

Have you ever played Monkey Island 1 2 or 3???

[mybike]

Originally Posted by OneLeggedRider

I forgot to include this about cold starting. With a. 45mm pilot and 3.5 washers on the needle it's getting plenty of fuel. At 75° I don't need the choke at all, and if I do put it on half choke I have to take the choke off immediately, and if I try full choke it will start but acts like it's drowning, I think I almost fouled the plug lol. And I really paid attention to the deceleration yesterday, I kinda miss the snap crackle pop.

I also need no choke down to 60 65 degrees. Bike starts real fast, in fact lately have been kick starting it because only needs one kick and boom fires right up.

Nice when they run right. And yes when tuned right these little engines pull pretty hard for what they are.

Enjoy your ride leg.

[dpl096]

Originally Posted by Merlin

Perhaps this is more to your liking:
https://www.dailymotion.com/video/x2hwqlw

Lol....its still nasty stuff.

[OneLeggedRider]

I'm not the carb tuning guru that Dan is for sure. But with my training and some trial and error I can usually get them pretty close. This stock carb did have me frustrated though, I almost bought the Mikuni. Drilling the pilot to .45mm was a definite improvement. And the 110 main didn't fall on it's face like the 115 did, but it was still lean throughout the circuits. The only thing left was raising the needle higher and MyBike had done it with good results.

I'm considering ordering Tako's 48 pilot and 112 main, maybe then I can have the mixture screw at 1.5 instead of 2 turns out. But maybe I'll wait until I do the head because that will throw everything out of wack again. Never ends lol.

[o2jmpr]

Originally Posted by Wild Dog

Have you ever played Monkey Island 1 2 or 3???

Attachment 17197

HA HA!!! Wild Dog, did we just become best friends? Do you want to go do karate in the garage? MI is a true classic and any reference earns my instant respect. Well played sir.

[OneLeggedRider]

Originally Posted by o2jmpr

HA HA!!! Wild Dog, did we just become best friends? Do you want to go do karate in the garage? MI is a true classic and any reference earns my instant respect. Well played sir.

I don't have a clue, never heard of the game, but I assume it's in reference to our spammer.

[o2jmpr]

Originally Posted by OneLeggedRider

I don't have a clue, never heard of the game, but I assume it's in reference to our spammer.

Yes, It was. Harmless fun, it was actually a really funny and witty post but you will need to devote ~80 hours of your life to the game/s to really understand the reference. It's a small group of people who "get" it.

[OneLeggedRider]

Took the bike out yesterday for an afternoon of sightseeing and spent about 4 hours on it. Well the highway to one of my destinations was mostly long drawn out hills. I thought the carb was on point but I discovered it's still pulling slightly better at 3/4 to 7/8 throttle than what it is at wide open throttle!

So when I got back to my area I did 2 speed runs on the flat straight stretch by the river. And sure enough, at WOT I got 63mph on the GPS and at 3/4 I got almost 66mph. And you can feel the bike pick up and gain power as you let off WOT. This is frustrating to say the least.

Do I actually have to go smaller than a 110 main jet? I do have the other 2 circuits running really rich, so maybe the sum of all 3 is a little too much? And I really don't wanna change the other 2 circuits because it's starting and idling great and has never pulled this hard up to 3/4 throttle, and it's running cooler with no popping on deceleration.

I'm hoping Dan and Jerry will chime in and give me their $0.02.

[OneLeggedRider]

Also the 2 speed runs were in the evening and WOT performs better with cooler air. I'd say that's because the air is more dense and getting more oxygen molecules in the air/fuel mixture.

[Merlin]

Originally Posted by OneLeggedRider

Took the bike out yesterday for an afternoon of sightseeing and spent about 4 hours on it. Well the highway to one of my destinations was mostly long drawn out hills. I thought the carb was on point but I discovered it's still pulling slightly better at 3/4 to 7/8 throttle than what it is at wide open throttle!

So when I got back to my area I did 2 speed runs on the flat straight stretch by the river. And sure enough, at WOT I got 63mph on the GPS and at 3/4 I got almost 66mph. And you can feel the bike pick up and gain power as you let off WOT. This is frustrating to say the least.

Do I actually have to go smaller than a 110 main jet? I do have the other 2 circuits running really rich, so maybe the sum of all 3 is a little too much? And I really don't wanna change the other 2 circuits because it's starting and idling great and has never pulled this hard up to 3/4 throttle, and it's running cooler with no popping on deceleration.

I'm hoping Dan and Jerry will chime in and give me their $0.02.

Have you looked at your plug?

[Weldangrind]

Believe it or not, I'd go a tad richer without changing anything else. Try a 112. Your comment about the cooler, denser air is the key.

[JerryHawk250]

Here's my $5 worth. lol I would do as weldandgrind said and try a 112.

[OneLeggedRider]

I haven't done a plug reading since I raised the needle further so that's something I need to do first.

I suppose I'll order a 108 and a 112 just to see which works better. But when I ran the 115 it really fell on it's face at WOT, and switching to the 110 was a definite improvement.

[JerryHawk250]

Originally Posted by OneLeggedRider

I haven't done a plug reading since I raised the needle further so that's something I need to do first.

I suppose I'll order a 108 and a 112 just to see which works better. But when I ran the 115 it really fell on it's face at WOT, and switching to the 110 was a definite improvement.

It's possible you need to drop to a 108. But you said it was cooler so that makes me think running leaner. Saturday I played with the jets on the PWK30 because its in the 90's now and I was tuned for the winter. I tried changing the pilot from the 39 to a 41 but was way to rich. I had a 125 main which is running rich now because of the heat. I only have a 115 and 120 main. I tried the 120 but too lean. I need to order a 122.5 and try that.