New rebuild, new carb, wont idle

You can remove the inlet side (rear) airbox boot. You'll get more induction noise and the filter will be exposed to water & more dust than it would have been. If you don't ride in heavy rain it's a non issue. Might need to wash the airfilter foam more often but that's no bfd either. Unless you're out riding lots of miles in the dirt, once yearly cleaning ought be mild overkill.

And, yes, old rubber parts can become crunchy in the extreme. New airbox boots are still available, as are cannisters, with new boots installed.

Update:
Got it pretty well dialed in or at least real close. Idles well and runs good. BUT, it just does not go past about 43 mph. Before the 88 kit it would run up to 47 bone stock. They changed the front sprocket to a 16 and left the rear stock. it pulls stronger than before and is quicker but once it hits a little over 40 it’s done. Any suggestions on what to do to get the mph higher?
i can start out in second gear with ease and switch up to 4th at a very low speed and it just pulls along like a tractor. Hard to complain too much but I was expecting to hit at least 50 with no problem while cruising at 40 but not so much.

You're right, something here isn't quite adding-up. Assuming full compression, the possible issues are: carburetion, gearing, cam.

If you have a stretch of clean road, then it might be worth doing a test run with an endcap removed from the airbox. Having a lean mixture, as a result, would indicate breathing restriction; in which case you'd rejet, then fix the breathing bottleneck whatever it turns out to be. If you find the missing mph, there's the problem...airbox restriction - inlet boot or filter element.

I don't know what your gearing is, kinda doubt that the motor can pull a 17t C/S sprocket. However, it's a cheap part, might be worth testing. Adding displacement increases torque and, all else the same, shifts the powerband lower.

Part of why the powerband shifts to lower rpms is an effect described as "bigger displacement making a cam act smaller". Again, I can't recall what cam you're running. If it's the stocker, then a more aggressive profile will help bring those extra CCs breath as the should.

Maybe the 17 tooth sprocket is the ticket then. Right now 1st gear with the 16 seems low. I can be in 4th gear at 10-12 mph and it just pulls right along. After the rebuild the motor has so much more low end and mid range torque than before. It seems to run out of steam at high rpm. Will also try the end cap trick as well.

It shouldn't run out of breath at high rpm. If it does, that's telling you that something is not right, i.e. there's a choke point/bottleneck. Think of the engine as a complete system, everything has to be balanced well enough to work with everything else...otherwise the end result is , even with good quality parts. The CL70 uses the same head...and was factory rated 6.5hp @10000rpm. All else being the same, 88cc should be capable of roughly that same hp level...but at ~2000rpm lower. That's the effect of increased torque. Adding more bumpstick would allow the engine to breath efficiently at higher revs...and that's where you'd realize more hp. I'd guesstimate somewhere in the 7hp range is possible from your 88cc setup...with cam, carb & exhaust optimized...with the engine spinning willingly beyond 9000rpm.

I don’t think I explained correctly. The motor revs up quicker than stock which makes me shift gears sooner than before. I am in 4th In places where I used to be in 3rd. It feels like I have 4.10 gears in my old car.

WAC TRL70 said:

I don’t think I explained correctly. The motor revs up quicker than stock which makes me shift gears sooner than before. I am in 4th In places where I used to be in 3rd. It feels like I have 4.10 gears in my old car.

Click to expand...

I get that. However, you said that top speed is down and that means lower peak rpm.

Typically, 3-speed/88cc tunes like 16t (one larger than stock) C/S and no more than 1t smaller at the wheel...all else the same. Procedure for dialing-in the sprocket combo, from scratch, is to upsize the C/S sprocket until the motor "falls on its face", then either drop back one tooth...or upsize the wheel sprocket by 1 tooth...effectively splitting the difference. FYI, a workable rule of thumb: "one at the CS equals two at the wheel".

Is the rear sprocket 45 tooth, as listed in the microfiche diagram? If so, I kind of think that 16/45 (2.81:1) is too low a gearing

Yes the factory rear sprocket that’s on it is a 45 and then shop changed the front 14T sprocket to a 16 tooth.
It’s either not revving high enough or it is but the gearing is limiting the top speed. That is what it feels like to me. The engine is sounding like it’s revving the same as stock. It’s sounds like it’s screaming at 40. With all this said it would do 47mph when it was stock with factory sprocket so something isn’t adding up. It’s just much quicker now.

Dont know how many miles you've put on it yet, but I get the feeling that your cylinder/ piston isnt quite broke in yet. Breaking things in properly has ALOT to do with performance and longevity in the long run. With that 16tooth CS, I would try a 38tooth rear, but thats just me.lol. My HK1 is supposed to have the 14/45 combo, but I would never go with that for the mostly open road ridding I do. I dont want it screaming at 35plus and 1st gear being basically useless. If I was off road all the time, the 14/45 is probably great. Go ahead and check your points setting. Set to .016. If it was set at, lets say, at .012, then it will definitely have better top end speed set at .016.

Stock, they're all geared for the same ~4.8mph/1000rpm in top gear. So it should've been spinning ~10000rpm, stock, at 47mph. That's 3 & 4 speeds alike. They don't like to pull more than that, in stock form. With a 52mm bore-up, low 5s is about all the torque can handle. Calculating sprocket changes is easy enough, using percentages.

FYI...it's been a long time since I crunched the numbers on a 4 speed. As I recall, both 44 & 45t wheel sprockets were listed in the parts manual. I suppose it's possible that some may have run 44 or 45t at the wheel and either 14 or 15t on the C/S. The tallest gearing would have been 2.93, the shortest 3.21. Mathematically, 10% taller would be between 3.21 (16/46t) to 2.64 (16/42t). None of this changes the fact that it's now slower. Some testing is called for. IDK, maybe try the stock sprocket combo, just to get a baseline. If top speed goes down, then you're way undergeared...time to try giving it some longer legs and retesting.