Topic: 750 doesn't rev pass ~5k

[ChopSticks]

Alright I finally solved the cold exhaust issue (pilots were clogged) put in new K ones
Air box is back on
Float heights good
Valve and timing set
Re sync the carbs

(Have not been able to do an idle plug chop yet my auto store ran out of plugs so waiting for them to ship)

Now finally got to take her around the block. Everything up until 1/4 to 1/2 throttleish revs/pulls perfectly. Once I get closer to 1/2 the bike RPMs stop increasing immediately. But if I let loose a little it back near 1/4 it starts increasing again until it maxes around 5k

Now I saw the chart floating around with the issues at certain throttle positions and it seems to be needle position and tapering? Believe the current position is 3/5

I did check the plugs after the ride 1 was lean 2,3,4 were carbon black but not oily. Again waiting for plugs to do set the IMS. With that said:

1. Should I change the needle position up or down? How many steps?
2. Can I adjust the needles without taking the full rack off? I have 675A carbs
3. How do I check the needle tapering? What are bad signs?
4. Should I wait for the new plugs to get the idle/IMS perfect before going to needle or are the totally separate issues?
5. When unclogging the idles I did notice my mains were probably not all matching. They're so old and worn I was only able to read "11" on 3 of them and figured it was 110, but then on the last one it clearly read 105. So I'll be ordering a new set of jets but figured since the mains aren't utilize until WOT it's not a high priority?
6. Current engine is 750F3 but the carbs are from K saw a chart that had 110 stock for K and 105 stock for F, which should I order? Also planning to get a 4 into 1 eventually from 4 into 2. Should I just order a couple sizes up 105,110,115?

[TwoTired]

Step one, imo, is to figure out why all the plugs don't show the SAME deposit pattern.  Tying to fine tune with all the carbs not behaving identical, is a chase your tail scenario.

[scottly]

I did check the plugs after the ride 1 was lean 2,3,4 were carbon black but not oily.


5. When unclogging the idles I did notice my mains were probably not all matching. They're so old and worn I was only able to read "11" on 3 of them and figured it was 110, but then on the last one it clearly read 105.

Have the main jets been drilled out?

[ChopSticks]

Alright I guess I'll wait for new plugs to do the idle chop and adjust the IMS. If the same issue occurs once all the plugs are the same what would be the next steps?

How can I tell if the main jets have been drilled out?

[scottly]

Have you removed and thoroughly cleaned the emulsion tubes?

[754]

That is important..   Sounds like something is plugged.

You plugs, you may not understand how to do a plug chop. You have to kill motor and coast to stop to check the specific range. You can do it many tines to one set of plugs.

[scottly]

Idle Mixture Screws are only effective for idle. I doubt there is enough range to make plugs sooty, even at idle.

[ChopSticks]

Emulsion tubes were dunked in a gallon of gunk and then cleaned with with a can of gunk when the original 3k was done but since the pilot screws have been clogged since then I'll definitely check those out.

754 - I was under the impression the idle plug chop had to be done first. and then trouble shoot /plug chop the ranges above that? but if I can use my existing plugs to do the higher chop in the mean time I can do that. but would it be effective to chop 1/2 or higher if the RPMs don't increase?

scottly - I was getting sooty plugs prior to riding the bike (why I was waiting for new plugs to test the IMS), but after the ride they were completely sootied.

[scottly]

Burn the black off the plugs with a propane torch before any further tests. My approach is to select the main jet first, then work my way down to pilot jets.

[754]

Did you run a wire thru the emulsion tube holes?
Could you see light thru the holes ?

 And when you now pull a bowl, is it clean EVERY time ?

[ChopSticks]

scottly - ohh didn't know you could do that, it doesn't harm the plugs at all? would definitely be more cost efficient. any idea if Butane gas would work? I'm in an apartment so not sure where to store the propane but can probably get my hands on one this weekend

https://www.amazon.com/Elephant-Lighter-Windproof-Camping-Grilling/dp/B01N3VQZ9F/ref=sr_1_2?ie=UTF8&qid=1499059351&sr=8-2&keywords=solder+burner

Also how do you test the main jet first? The throttle doesn't get passed 1/4 without bogging

754 at the time pretty sure I could see light through, but I'll be sure to stick some wire thru the holes when I pull them

The bowls have been surprisingly clean lately, aluminum is mirror shiny. I did notice some grit a few weeks back when I was getting the whole thing back into shape, but could've been from auxiliary tank I was using since the gas tank has a brand new petcock. But haven't seen it in a while

[754]

Soft wire. Like copper.
 If it starts a runs you can probably use those plugs. You cant check the mains till it revs out. And should not close throttle when doing a plug chop.

[scottly]

Do not burn off the plugs inside your apartment!!!

[ChopSticks]

754 - if it starts a run? So I should plug chop after idle even if it doesn't rev pass the pilot?

scottly - lol oh definitely, just not sure if it's okay to store propane INSIDE my apartment. Will the butane suffice?

So far for today's checklist I have:
Pull main and emulsion, clean with wire
Torch off plugs
Do idle chop

[flybox1]

1. Should I change the needle position up or down? How many steps?
2. Can I adjust the needles without taking the full rack off? I have 675A carbs   Take them off the bike.  Its easier and you wont strip screws
3. How do I check the needle tapering? What are bad signs?  Not important at this moment.
4. Should I wait for the new plugs to get the idle/IMS perfect before going to needle or are the totally separate issues?
5. When unclogging the idles I did notice my mains were probably not all matching. They're so old and worn I was only able to read "11" on 3 of them and figured it was 110, but then on the last one it clearly read 105. So I'll be ordering a new set of jets but figured since the mains aren't utilize until WOT it's not a high priority?  Jetsrus.com  Buy jets for the CARB YEAR, not your bike year.
6. Current engine is 750F3 but the carbs are from K saw a chart that had 110 stock for K and 105 stock for F, which should I order? Also planning to get a 4 into 1 eventually from 4 into 2. Should I just order a couple sizes up 105,110,115?

Have you done a clear tube test and verified good fuel levels?   If not, before you get to your idle chop, get this done.  bowl fuel level impacts A/F mixture.  It needs to be accurate.

[754]

I would concentrate on getting it to rev, if it cant do that , you wont be riding it..

[ChopSticks]

flybox1 clear tube test was actually done couple nights ago when I found out the pilot screws were clogged.

754 other than clogged emulsion tubes & float height any idea what else would prevent it from revving? 

[flybox1]

flybox1 clear tube test was actually done couple nights ago when I found out the pilot screws were clogged.  Cool.

754 other than clogged emulsion tubes & float height any idea what else would prevent it from revving? Incorrect air/fuel mixture, poorly timed ignition/advance...

[754]

Clogged mains..

[ChopSticks]

Alright just to update: pulled the emulsion tubes last night and to my surprise I think I have a good idea why after 1/4 wasn't revving. 3 of the 4 main jets were in the float bowls 

When I cleaned the pilot jets this past weekend I did check the mains and only finger tightened them since the last time I tightened I snapped the whole carb body (that's another story).

Back to the emulsion tubes, 2 & 3 I couldn't see light out of the small holes near the bolt side. So I took carb cleaner to all the pilot, main, and emulsion tubes. I see light through all of them and carb fluid sprayed out of all of them. By the time I got everything reinstalled it was too late to do a test run but will do that in a few and update.

Also got a Butane torch since propane and MAP gases apparently aren't allowed to be stored in "living spaces."

Lastly reconfirmed 3/4 jets were 110 and 1 was 105 so I'll put in an order to jetsrus thinking of getting 110,115,&120 for future mods?

[ChopSticks]

Was able to take her for a spin last night, doesn't bog around 5k anymore but struggles a little to get passed 6-7k not sure if that's just how the bike is or should it smoothly go up to 9.5k in every gear?


Also now I'm a bit confused on which jets to order. I have 657A carbs and the link below

http://www.hondachopper.com/garage/carb_specs/carb_specs.html

Says that the mains are either 105 or 110. The engine I have is a F3 but the frame is K4 which would fall into both of those categories...

[madmtnmotors]

Lastly reconfirmed 3/4 jets were 110 and 1 was 105 so I'll put in an order to jetsrus thinking of getting 110,115,&120 for future mods?

Before you go any further, get matching jets in all four carbs fcol...

[seanbarney41]

I have 115's in my F3 with 7A carbs(657 are very similar but may have different pilot screws, needles, and needle jets), stock airbox with K&N filter, lightly baffled Jardine 4-1 with long megaphone...should rev beyond 9200 redline (but don't do that, it's just not necessary!)

[ChopSticks]

I have 115's in my F3 with 7A carbs(657 are very similar but may have different pilot screws, needles, and needle jets), stock airbox with K&N filter, lightly baffled Jardine 4-1 with long megaphone...should rev beyond 9200 redline (but don't do that, it's just not necessary!)

What are your thoughts on the Jardine? is your F in a K frame? just curious if you had any issues bolting it to the frame

I don't plan to ride at WOT just wanted to make sure the RPMs were increasing, assuming to be able to redline would involve proper fuel flow and main jet right?

[flybox1]

+1 - all jets should be the same size (and Keihins)

If you are jetted properly, it should feel like it wants to continue to pull through redline in each and every gear.