low end chug

[Biggyfaction]

alright been working on this bike for awhile now. rebuilding piece by piece. got to take it around the block and its sluggish/chugging on the low end. ive read the posts on the pickup wires. gunna check those out again seemed fine when i had it opened and ran a new vacuum line. also noticed when it gets to a higher rpm it revs up but it feels like it slipping.

[donebysunday]

Are you using and old stock exhaust, they can rust up inside and clog the flow, one sign is bulging in the muffs/rings around them that look swollen. Also had one with a dented inner pipe, how ? All in can figure is it was made that way or got water inside the outer and inner and was allowed to freeze ? Outside looked great, took a while to figure that one out.
Can you tell if the clutch is slipping or the engine wants to go but can't ? There are many other causes, I believe you have mechanical advance, is it working ? Lots of things can happen from sitting so long. I take it you went through the carbs, have stock jetting and all passages were checked for flow. Hear any noises when this happens ?

[Biggyfaction]

exhaust is not stock. i put 1 3/4 inch pipes off the 4-2 collectors. i have it baffled im wondering if i have too much and its clogging. the vacuum advance is working as far as i can tell. it moves when i use the throttle. jetting isnt stock im running 120 mains instead of 110. when i take off it feels like the engine is struggling. then it opens up the engine revs and theres no pull. let off the throttle and do it again to pick up speed.

[donebysunday]

You put nice big pipes on the headers but what did you use for baffle and how much ? Big jets for more fuel/richer mix and the baffle combination could be a problem. Does sound like the clutch is slipping.

[TopCatGr58]

Hey Biggie,

I reviewed your earlier post with the photos of your FIND! You have mentioned getting the electrical fixed, and got the vac. adv. put on the correct carb nipple instead of the intake boot where it was. But the Vac. adv. is mostly for fuel savings. The Mechanical Central Adv. is what provides the timing advance for POWER! At first you had said that your bike was an 81LH, but then later I read that it might be an 80 LG. Did you ever check the VIN# against the thread in the MISC forum and confirm your year...the side covers looked like 81 to us?? The 80 will have mechanical adv, the 81 will NOT, just vac. because the Mech. Adv. curve is programmed into the TCI. IF it's an 81, the TCI should say 4RO/1 vs. 2H7 for the earlier mech. adv. versions.

Also, the original thread photos showed NO carbs on the bike, we have to assume that you have cleaned them, but did you truly take them fully apart down to the emulsion tube/main jet nozzle as well as pilot jet, pilot/idle screw and float valve/seat, etc. all removed and all circuits cleaned with carb spray or bodies soaked in PineSol and then rinse, blown clean?? And what are the Pilot jet sizes....you told us the MAIN jets are upped. What type of air filter...OEM box or Pods???

There's a clutch adjustment that is to be done on the side of the engine, you talked about the 3 bearing/balls for the throwout lever, but did you set the push rod to the proper point...~ 1/4 turn backed out from gentle touch and locked? What oil did you put in it? With worn/weak springs SYNTHETIC can aggravate slippage! As has been mentioned, old springs loose their tension and can cause slippage even with IN-Spec frictions, best fix is to replace with Barnett springs! Also ensure the clutch cable slides freely/easily, corroded/rusted cable and also cause clutch to NOT fully engage which can also cause slippage.

T.C.

[Biggyfaction]

i tore the carbs apart fully and dipped them the first time no problems. i found a broken wire on the pickup. fixed it. pilets are upped 1 size. ive rode the bike before and it had plenty of power no chug just a slight slip. i took a look at the clutch cable. it works on the bike but off the bike its frozen. gunna order a new extended cable. once i got spark, number 3 got warm but 1 was still cold. started tinkering with starter fluid. ran great for a sec then i shut it down. then took my air nozzle and checked passages. i took my carbs off again. i had some corrosion from the tank get into the carbs. the bike doesnt have petcock screens so i got some from my buddy. cleaned the carbs again. still have to reinstall carbs,screens, fuel filters and custom velocity stacks. need to get tank dipped and sealed. got some of my paper work on it. its a 80LG vin starts with 4H3.

[Biggyfaction]

i have 20-50 in it. the pipes are the same size as the headers. still only 4-2 exhaust with 6 inch baffle in each side. the velocity stacks fit over the stock air box boots. have screens and uni-foam for filtering along with a dust bag cover. built them from stuff found at the hardware store under $20.the first time i rode the bike it was great except for the starter needed cleaned. power was right there especially with a 1/4 throttle. the slipping was there but not as bad. the clutch lever was getting stuck open when id go to use it. took the cable off and i cant move it by hand or with pliers.

[donebysunday]

I'd take all but the screens out/off of the velocity stacks and test run it, after a new clutch cable of course. You may have restricted the air flow with the foam and dust cover ? Running it for a bit on a dry and clean road should (no dust or sand) not hurt, you will still have the screens in to keep out the big stuff.
BTW what velocity stacks are you using ? Got a pic ?
I imagine the baffles are not removable ? If they are and the problem persists after the stacks are opened try taking the baffles out, test run again.
One thing at a time to determine which thing is causing the problem, just like building it one thing at a time to see what that one thing does to your performance. I just cleaned the tank from my parts bike and small bugs and dirt came out with the flush. I did the flush with local pump low grade and a bottle of Berrymans fuel system cleaner. You can't see the really small dirt particles and the in tank filters can't keep them out, so yes add in-line paper or brass filters from the MC shop.
I re-read your last posts and take it you made the velocity stacks ?

[Biggyfaction]

yes i made the stacks out of 2" pvc 45 degree bends i sealed some aluminum screens in to make a holder for the foam and the dust bag. the airflow is good. i had a problem with spark. now i need to clean the tank put the screen tubes in and build new fuel lines for the setup i built. the bike was fine untill last week. ive got the carbs blown out and cleaned up again. after i put in the screens and filters ill try it again and start over to make sure i can get as much power as i can without causing any damage. this bike was a challenge to those that say you cant build a bike without buying all new equipment and tools. i have less than $600 in the bike and most of that is from broken electrical equipment.

[wjw11teen]

i had similar problem on my 81 special

i bought the rebuild kit for the octo and petcocks that was recommended from a member on here

it seems to have worked....no more chugging and more bottom end snap