Hawk tune up, top speed, and general musings.
 

Well it's coming up on 600 miles so I figured I was past the break in tune up time. The valves and chain were loose, and oil change was long overdue, and the muffler was rubbing the tire at full suspension compression.

The muffler was simple, just a trip to the hardware store for a longer bolt and 5 washers. The 520 O-ring chain had stretched alot, I was actually concerned about riding it lastnight. But 2 turns on each adjustment screw fixed that. The oil was remarkably clean, I figured it would have a gray color, and there wasn't any metal in the screen. So I'm real happy about that.

I had set the valves at .005" for the break in and I figured they'd be tighter now but they were actually looser. I set them to .003" and hopefully won't have to worry them for a while. I also added 1 washer to the carb needle for a total of 3, but haven't test ridden it yet. One of the intake nuts fell down into the sprocket cover so I had to pull the shifter and cover off to retrieve it. >:(

Yesterday I checked the top speed with GPS and the stock speedometer is way off. In the heat of the day it ran 58mph and 63mph in the cool night air. Also I'm impressed with the brakes. I popped over a hill on an unfamiliar paved road and had about 30 feet to turn right or left, so I locked up the rear wheel momentarily and grabbed a handful of front brake! There might be a small hole in the seat from my sphincter tightening up.. :lmao:

She's running pretty good considering you are geared low. :tup:
So how's the new leg training going? I'm still amazed at the technology.

What is the app you are using (is it Live mobile location and ...... or is that something they are trying to sell you)?

Just says "GPS Speedometer" on Google play store.

I'm not running out of gear at all, running out of power. This thing makes nothing on the top end. I can actually take off faster by not letting the gears wind out.

The leg is doing great, when it learns a new activity it never forgets it. And just like the Cyberdine Systems technology it can't be shut off, I can power it down but it's still on and still recording. If it learns how to charge itself we're all in trouble.. :lmao:

From my experiences, even though the engines do tend to mostly break in around the 500 mile mark, it can take upwards of 1000 or so before everything is fully broken in. Especially on that last little bit of top end. Even so, what Jerry said, and what you said, are both accurate. You ran out of gear because you are running past the powerband via RPM. If you went even taller out back it would pick up more top speed by shifting where you are sitting in the RPM range in 5th. Stepping down from a 45 to a 43 rear on my last Hawk made a big difference in top speed by placing the RPMs lower into the stronger part of the power curve at those given speeds. You do start to notice a good hit in the acceleration department

Even though my head porting opened up a bit on the upper end of the rev range, I can tell that the carb size is a small limiting factor, but the cam profile is still going to keep this motor a bit flat on the top end. That is why I can run up to the 65-70mph mark usually with little effort, but the 70-75 range it starts to fall off and struggle, and anything past 75 takes a total planetary alignment and perfect conditions. If I geared up a bit more it is likely my top speed would change very little, but how it pulled at those speeds would be very different. I just don't want to lose the acceleration that I do have in the lower gears to achieve that.

I am considering seeing what it takes to make a 14 tooth front work. I know the 13 tooth is a bit tight, but unlike a 17t 428 sprocket and chain, I can still remove and install my sprocket cover with ease. That tells me there is a little room to play with, and I have no issue removing material from it if it will allow it to fit. That would open up the door to front sprocket swaps so I can easily change between road only and better off road gearing.

Well I know I'm not changing that 33 tooth rear sprocket until it's absolutely necessary lol. But I will go ahead and order a 13 tooth front sprocket just to see if I like it. I haven't been off roading it as much as I thought I would and first gear is really low, I have to shift into second after just a few feet. Damn thing should come with a 6 speed transmission.

Also the seat has gotten more comfortable for me because I'm making myself sit further forward, feels like I'm sitting on the handlebars though.

Gonna test ride the carb needle change in just a few, it was just too damn hot out there. 86° and really humid.

The verdict is still out on adding a 3rd washer to the needle. Just took it for a little spin and really couldn't tell any difference at all. Guess I'll have to take it for a longer ride tomorrow and see if it affected top speed, plug color etc.

Well the verdict is in on the 3.5 washers. Due to inclement girlfriends and nasty weather I hadn't gotten a chance to go for a long ride until yesterday. I think I've found the sweet spot. It's running better than ever now. No hesitation off idle and pulls strong throughout the midrange. The valve adjustment probably helped some too. I haven't had a chance to do plug readings, but the pipe is putting off less heat and the snap crackle pop on deceleration is almost completely gone.

I got the idea from I believe MyBike? The guy with the customized Magician. He put 4 washers on the needle and didn't go really big on the main jet, and raves about how well it runs. The reason I say 3.5 washers is because the local hardware didn't have the thinner washers I originally bought and this one is about 1.5 times thicker.

So with lots of trial and error I'm at .45mm pilot jet, 3.5 washers on the needle, and a 110 main jet with 2 turns on the mixture screw. And it's really running well, the exhaust note even sounds a little different if that makes any sense. Now should I drill the pilot to .5mm, or put it on the shelf and start over with the Mikuni clone?.. Hahaha! :lmao:

Why not buy the simple “first tune kit” and or go to a pumper carb using same type of carb
Both are more economical then changing to mikuni and pumper gives a gain st only a little more $

https://rover.ebay.com/rover/0/0/0?m...2F303077495104

https://rover.ebay.com/rover/0/0/0?m...2F303169447550

Good old Tako, always trying to make a sale Haha! Why would I need a "first tune kit"? The only thing I could possibly need is a 112 main jet and I can get it delivered in 2 days. And the bike is running great now, so what advantage would I get from a pumper carb when I'm running a stock head? If you wanna do something useful find me a better camshaft or a head that's already been decked ported and polished with better valve springs. :tup:

All you need to do is invest in a $20 rotary tool and some burrs and get busy. ;) I can confirm the TT250 head is a better casting and less restrictive on the exhaust side. Decking can be done manually with sand paper on a flat surface and a little elbow grease. lol We are only talking about taking 1mm off the head. You can even use a thinner head gasket if you don't want to machine the head. We have one member that installed the TT250 head and thinner gasket and found an improvement with no modifications to the head.

I've already got the dremel and all the necessary goodies, and just this morning I priced a TT250 head at $85 plus shipping. I'd have to order some measurement tools but I should have them anyway.

My my.. :lmao:

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.

Wow, I thought we were better than this on this forum. Thanks OneLeggedRider for bringing this to light.

If you add a few more items like head gasket, brake pads and so on to get it over $100 you will get free shipping. You might as well get the few extra part for the cost of what the shipping will cost. :tup:

Good thinking Jerry. I wonder if the TT250 head gasket is any thicker or thinner. And is there enough clearance in the frame to pull the head without pulling the motor?

From what one of the other members stated in his thread it was a thinner gasket. There is plenty enough room the remove the head without pulling the engine.

You weren't rude, at least not by my standard, and I agree with you 100%. Anytime somebody mentions the mikuni, *poof*

https://foodsafetynewsfullservice.ma...te_300x380.jpg

I guess it wasn't obvious before with my many interactions.


Yep, plenty of room to pull the head. I actually did a video on it, though it isn't the greatest.

To touch on a different point. The pumper carb would be advantageous on a stock engine as well, especially one with an exhaust and intake. No need for head porting to take advantage of it.

Damn it Dan.... That stuff is disgusting..,. Puke

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

Took the bike out for 3 hours tonight, and I have definitely got the carb right. This thing is pulling so hard, idling so well, starting so good, etc.. It did stall on me one time in town because of clutch fade, but I know an oil cooler will fix that. And I'm gonna order a 13 tooth front sprocket for more speed, I can always switch sprockets if I'm going riding at the Reclaim. Also figured out 5 washers on the muffler wasn't quite enough, but I can live with it barely touching at full suspension compression. Loving this bike! :)

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. :yay:

My Hawk behaves the same way. I have two .032 washers on the stock carb needle. No choke is needed unless it's quite cold and then half choke for only ~10.15 seconds. Full choke will always kill it. I'm running stock pilot though so I always turn my idle set up 1/4 turn to start and warm for a minute then turn it back down to where it sounds right. I do still get some light popping when decelerating but I just quit worrying about it. Glad to hear your'e stoked!

IIRC, Megadan once posted that above 80, choke ususally wasn't necessary but probably still recommended. 60-80 was half choke range and below 60 full choke. Of course, he has his tuned to perfection I'm sure and you both definitely know what your doing more so than me. I will say that other than regearing to 17/45 for my weight and riding environment, the oil cooler install was absolutely the best investment I've made for the Hawk.

That would be worthwhile buying a complete kit with updated head ,a head gasket or 2 ( one thin and one thicker ) or maybe better ,an option on which gasket you want. Not sure what all it takes to change the cam but offer a reprofiled cam with necessary gaskets and hardware.

On another note does the TT250 head come with valves and springs etc or do you have to transfer you bits from the stock head .

Hmm your idea has got me thinking, Offer it in stages such as:
#1 Ported , polished and decked head with gasket/s.
#2 A cam kit plus necessary hardware and gaskets to complete the install.
#3 All the above plus a pumper carb with a jet kit to fine tune plus a pod filter.

Maybe someone could do it on an exchange basis, or NZBL could really put together these ideas as he has access to cheap parts and possibly cheaper labor.

Just food for thought.:tup:

The TT250 head is just the head. You will have to transfer all that from the stock head. Be sure to order extra valve stem lockers. I lost one when I did my head and had to wait about a week to get one from CSC.

Thanks Jerry, I've read a few times about upgraded valve springs? Are the stock ones not very good/durable or is it because people want to rev the engine higher than the stock 8500 rpms.

I don't see any problems with them. These engines aren't really design to run above 8500 rpms. That's well past the power band.

My bike is tuned in about as close as I can get it with what I have. The 45 pilot is actually just a bit too small, but it is not too lean by any stretch either. The idle mixture has to be out about 1/4 turn past 2 turns, and it has no hesitation issues under light throttle. I consider this close to a Honda factory tune for the pilot/slow jet circuit which is always a touch on the lean but safe side of things. A 48 pilot would be the ticket for me, but I await a new carb, so it is moot at this point.

The temp ranges for the choke that I gave is just a rough guideline, but you are fairly accurate. It is just another way to judge how good your idle mixture is tuned in. If you need full choke on a really warm day (above 75 to 80 degrees) with a "cold" start, then you are likely still a bit lean on the idle mixture.

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.

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

Attachment 17197

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.

Lol....its still nasty stuff.

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.

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. :lmao:

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.

Back to the drawing board.
 

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.

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.