| Author | Message | ||
     No_sprk |
so s1 has been running fine since i put the new carb on. so yesterday i get in the mail one of the standard harley "horseshoe" style breather. i install breather, reinstall support plate and CF can ham with American Sport Bike billet backing plate. go to ride the bike and it sounds like shit. sounds like its SLIGHTLY missing on a cylinder. popping alot on decel. pull n check plugs, looks good. new wires and new plugs. so somehow i have the bike running and i remove air cleaner. all of the sudden its running fine, i mean i started to loosen the screws for the billet backing plate and all of the sudden it runs fine (idling fine, when its running like shit it doesnt like to idle) so im sitting there slowly tighening and loosening my backing plate and i can hear the bike running better/worse. i changed the gaskets when i removed carb support plate. i ended up saying •••• it and re-installed everything with an extra gasket between the backing plate and carb. somehow that helped a little but still not 100% im sooooo stumped. | ||
| Buelliedan |
what carb are you using? if it is a CV make sure you are not blocking the vent hole in the front of carb by the gasket. | ||
| Lynrd |
Odd. Never had that problem with that backing plate - in fact it was still on Veronica when Fireman Jim Dyno tuned it and produced the Horsepower the S3 was advertised to have in 1998. Sounds to me like the backing plate is pulling something cattywampus when torqued down (obviously), and introducing an intake leak. To check, get it running with Air Cleaner on, squirt some water or WD-40 on the intake manifold where it joins the head. Take care not to get anything down the throat. If the idle changes, there's yer leak - but, obviously, change all three seals while "you're in there". The damned seals on the intake manifold are a bit failure prone. If yours are old and stiff (rather than young and flaccid and doesn't that sound dirty) the new angle of the dangle may be introducing a pinhole leak. | ||
| No_sprk |
everythings been fine till i went to install the new breather. only thing that changed is a washer between the head and new breather tube. i rode it down the street with the long screws in the carb just holding it to the support plate. bike runs fine! no popping and idles perfect. tighten up and boom its shit... ugh it was just running great too. since the carb can float on the intake flange im thinking somehow something is tweaking the carb. thanks for your help Lynrd... btw id like a copy of that S2 picture  | ||
| No_sprk |
vent hole is not blocked. yes its a stock cv40... so the bike has been fine and after i installed the new breather thats the issue. i even took the breather plate back off and kinda wiggled the carb. checked vent hole. checked gaskets. i rode it yesterday after getting it OK. runs OK but feels slightly laggy and yes lots of lean popping on decel (not like before) | ||
| Brother_in_buells |
Is the rubber gasket between carb and manifold still in good order or did you replace that to? | ||
| No_sprk |
That was fine. I haven't removed the carb. All I did was replace breathers for generic horse shoe style. Carb did not move. I can remove air cleaner and it will run fine. As soon as I tightened down the billet American Sport Bike can ham backing plate it will run like crap. Leave it loose and it's fine. Really strange. It's like the carb is warping. The only difference in mounting position is the Thin washer behind the same carb support plate as before | ||
| Two_seasons |
I'd say you have manifold gasket leak(s) on the cylinder side or it's your o-ring between manifold to carb. I've broke several backing plates (breathers to CF hamcan), all chrome, until I installed NRHS black backing plate. Was told chromed ones make the metal more brittle. You'll find it... (Message edited by two_seasons on July 14, 2018) | ||
| Two_seasons |
By the way, check and make sure both sides of the bracket are intact, no cracks. | ||
| Brother_in_buells |
Maybe a silly thing , but did you use the same length bolts as they were for mounting the backing plate to the carb? | ||
| No_sprk |
Yeah I used the same bolts but obviously they were too long to fully seat. I just didn't wanna ride down the street with zero carb support. So to clearify I had no issues before the breather install. I doubt the backing plate is the issue. I just installed double gaskets on the carb to support plate and double on the support plate to air cleaning backing plate and tightened them up. Back to normal after a few blocks of riding... Going on a longer ride now. Will report back. Thanks for the fast responses guys | ||
| Two_seasons |
If you are double gasketing, that implies that the mounting surface is not level. | ||
| No_sprk |
yeah its wierd. the same OEM carb support plate was used. the only difference was a very small thin washer placed between the head and the carb support plate. rest of breather goes in front of support plate. yeah it sounds like somehow something is getting out of wack when i tighten it down. during my fairly long ride (on an S1) i stopped for a smoke break. after leaving i felt the bike start to do it again (idling crappy, lots of decel popping) and eventually it mostly went away. i know this is just a bandaid. just pissed about my running light issue i fixed just to have this come up. all i wanted to do was ride yesterday. today ill rip the carb off and swap it with another. thank you guys so much for all the help heres a shot on HWY1 north of Jenner  | ||
| Two_seasons |
 There is a very large shark out there... Looks like some of the route I took long long ago. Best wishes my BadWeb friend. | ||
| Brother_in_buells |
It's probably one of the three rubber gaskets because when warmed up is goes away. Manifold gaskets or gasket between carb and manifold. I would guess the one between carb and manifold | ||
| No_sprk |
yeah that makes the most sense. the ones at the head could be bad but havent given any issue before. i just dont understand how MM of differences could make that thing leak. problem is around here everyone wants $50 for some crappy james rebuild kit so ill have to check with the dealer to see if they carry just intake gaskets.. or look in the parts for my twin cam | ||
| Brother_in_buells |
https://m.ebay.com/itm/Harley-Sportster-XL-Intake- Manifold-gasket-set-88-2006-repl-OEM-27002-89K-/29 2142890367?_mwBanner=1&_rdt=1 | ||
| No_sprk |
I live an hour north of SF in a heavily populated area. Harley dealer and some smaller independent shops. If I bought most of my parts online I'd be waiting weeks to finish anything Thanks for the help with the link BTW :-) | ||
| Mike_lee |
Nice pic  | ||
| Ratbuell |
It doesn't take much of a leak to cause a running issue. It doesn't take many mm to cause a leak. Adding a washer can certainly cause it. Here's a thought - take the washer OUT, see if the problem resolves itself. | ||
| No_sprk |
ok so i have no idea whats going on but i got it to go away for now. undo air cleaner backing plate, still running like crap... take off carb support plate and remove thin washer that i inserted when changing breather, no change (may have gotten worse) so i add washer back on and reinstall, this time leaving breather bolts loose and tightening carb backing plate to carb. THEN i tightened down the breather bolts. bam! its running normal again... for now. just did about 10miles on it. soo for some reason maybe the plate was getting out of wack. finally came to me yesterday, if the only thing that changed is the damn breather than thats what i should be looking at.    | ||
| No_sprk |
so an update. after trying to remove the thin shim washer with no sucess i decided to get to the root of the problem... what changed? the breather! so i tightened the backing plate to the carb THEN tightened the breather head bolts and boom... no more issues. so somehow that breather was tweaking the carb support bracket. i think because its a original with one open and one closed end (Message edited by no_sprk on July 26, 2018) |
