Topic: Looking for experienced advice..

[mrbreeze]

Looks like the shocks you put on are too tall.Measure them eye to eye and report back. How does your side stand land? Bike dips too much? Sits up level?

[Stev-o]

Something is just not right.  Is the front wheel 19"?

I've had a bike with a 16" rear wheel, I replaced it asap with proper size and all was good.

How old is the 18" tire? You, as a tire guy, should be able to determine that quickly.

[754]

So tell us what tire is on what wheel . And check rear shock length
  I am not going to tell anyone they should ran an 18, it's up to you. Seen too many guys cornering way faster than me on 16 inch. Have you ever read a road test on a Kawi LTD ? Do they say the rear wheel has to go ? I sorta doubt it.  I have run on cb ' 50 rear 15, 16, 17 and 18 inch. Myself I rode corners a lot harder with a 16, than 18s   part of the reason we ran them , better tire life, better traction  for streetracing.

[JerrodR]

The 18" has a 140/90, and the 16" has a 130/90, the shocks i put on it are 13 1/2 inch's from bolt to bolt.. it not only handles much better, but it accelerated noticably harder with the 16", Also when I rebuilt my top end I replaced the cam it came with, with a Hondamatic Cam. That also had a significant improvement on acceleration. I believe i may have lost a little on the top end. But the way she pulls from a dig now is totally worth any loss in top speed.

[754]

Are the top of your forks flush with the top triple tree? Or slid up past ?
 They look close to proper in your pics, does fork have a lot of sag ?

[Don R]

 Make it suit yourself. Spacing the fender down with threaded spacers is an interesting idea. I did that on a KZ1000. I shortened one on my drag bike by drilling out the spot welds from the mounting bracket, cutting off the front, moving the fender forward on it and welding it back on under the aftermarket tail light housing. It was an old fender damaged by an overloaded rack so it was junk anyway. That will make a stock tail light look awkward though. 

[low-side]

A 130/90 X 16 is probably pretty close in OD to a 4.00 X 18 (maybe 3/4" smaller), so your geometry probably hasn't changed too much.  Raising the tubes in the tree the same amount might compensate for it.  I would check the swingarm bushings, the steering head bearings setting, and the condition of the fork tubes if you're concerned about how it acted leaned over.  According to the tire fitment charts I looked at, you would need a 3" wide wheel to take a 140 tire, and most 18" Lesters were 2.15" wide.  If that's the case, the tire would have been pinched, making it taller than it should have been and distorted the profile so that it would tend to flop into curves rather than roll.  A 110/90X18 is the max size for a 2.15" wide wheel and would be very close to original diameter (maybe 5/8" taller than where you're at now).  Your threaded spacers idea should work pretty well and will allow you to change back if you ever decide to go with the 18" wheel.  BTW, if that's a 18X3 Lester, we need to talk.  Good luck with it, it sounds like you're well on your way to making it your own.

[JerrodR]

Ok, both wheels are 3.5 wide, and as of right now the 18" (which is what it came with) has a 140/90, which become's way too tall when mixed with the shocks I have. Enter the 16" which I have a 130/90 on it, perform's very well with my shock's. Only issue Ive ever had is with the bike leaned way over going around a hairpin turn, probably a little too fast. The 16" perform's great under everyday situation's. But it has what I believe to be the stock sprocket, which is 48 tooth, which has me turning just above 4K at 55 MPH. I do not like this. So my plan is, I'm gonna replace the bearings in the 18" paint it, and get it looking good again. Then fit it with a 140/60, or maybe smaller tire, and a 38 tooth sprocket. If that doesn't bring my cruising RPM down enough then I'll go from there, until I can get it right, and then the 18" will live in the bike. I will keep the 16" just the way it is in reserve, because I like the low end grunt it gives the bike if I'm in the mood to play. But most days I am not. This bike is actually my daily. So I wanna get the 18" into a low rev configuration..

[JerrodR]

And guys I'm telling ya, the 2 inch difference in the wheels is making a huge difference in my situation. The 18" with the 140/90 is scary at times. At least with my shock's. The little 16" does very very well. And it really does accelerate harder, we can do the math all we want, but with my shock's the 16" perform's very well, that's just all there is to it. But from what I'm learning, I can get the 18" to perform just as well, even fix some issues I'm having with the bike as a daily, like high RPMs at cruising speeds. It will take away from my low end power, but I don't need a 4 second 0-60 when I'm just trying to get to work and back everyday.

[JerrodR]

But I will say, the Hondamatic Cam and the 16" wheel will wake the bike up some, my little 750 pulled the 19" Lester about 4 inch's off the ground going into 2nd the other day, while I was destroying my brother's 99 Sportster 1200 from a dig. I rolled into first, and stabbed it at around 6K and when I hit 2nd it started coming right up on me. I had to let off because I wasent ready for it to do all that lol. Still gapped em by probably 2 car's after a quarter. I really do love this old bike ❤️ lol.

[seanbarney41]

Well Jerrod...since you got it all figured out, thank you for your advice.

[Old Scrambler]

Sean.............+++1............Based on the photo, the FRONT tire is oversized

[madmtnmotors]

Your original post indicates "74' CB750", yet the tank, sidecovers, and carbs all indicate 77/78. I know the 78 K model came with a 17" tire, but I'm not sure that swapping back and forth from a 16" to an 18" rim will cause that dramatic of a difference unless other (non stock) components or excessively worn components are factoring into the equation...

[754]

77 and 78 K may have different final gearing the F sure does bad I am frigging tired of it , and the #$%*ty mileage I get..