Forum

[Michael]

I recently fitted a replacement exhaust and silencer (ahem!) to me EFI bike. The pipe is the standard Indian one, the loudener (er, sorry, silencer) is our hosts 90180 product. I am really happy with both; they look and sound great. And I have really noticed a difference in my bikes overall performance too. However, some differences are improvements and some are not...




The bike now has more appreciable power at the top end - I assume that the new system is clearing the spent charge from the combustion chamber more effectively at high revs and the extra oomf is the result of this? The throttle also feel much more responsive, almost like the big old silencer is no longer choking (not choking as in cold start enrichment though!) the engine up. Does my analysis make sense to those that understand things better than me?




The downside is that the throttle is also much more jumpy. I even had a slight kangaroo moment today, and it is especially jumpy on take off now. Why would my new exhaust system impact on this? Or should I look somewhere else? Secondly, I now backfire occasionally (not me, the bike!). This occurs mostly on throttling back to idle, and is more common when I quickly close the throttle, e.g. for braking quickly. What might be causing this/these issues? Are they related?




Finally, when I first fitted the system a couple of weeks ago, I felt that the engine was running a bit hotter than usual. It might have been the weather and the residue oil and grease on the new pipes, but I swear it just felt hotter. This has calmed done now, and it seems to be running cooler again. Is this a by product of my new system, or is it things adjusting through the ECU?




Any comments or suggestions appreciated

[Tomshayes]

Hi Michael.

Not being an expert in Efi etc and coming from a carburetored bike angle.. The backfire you speak of is probably because your bike is now running leaner as you have allowed it to breathe.. With a standard Carb set up I would usually expect to fit a richer jet to compensate for the derestriction of the exhaust.

Mr H can probably give you a better idea and probably does a tweak kit for the Efi unit. Hot running is also a sign of weak mixture..

Tom

[John M]

I suspect that the backfire will be due to air being drawn into the system, possibly due to poor sealing where the new silencer joins the old system, or at the exhaust port if the front pie has been disturbed. I would re-real the joints, silicone sealer is surprisingly good for this.

[Michael]

New pipe also fitted... with a new sealing ring/gasket. I take it the new sealing ring alone isnt enough then, and I should have used some kind of sealing compound too?

[Michael]

Had a look last night at my exhaust, alongside trying to solve my 'other' issue... there was a bit of carbon build up at the join between the silencer and pipe,so I cleaned it off and nipped up the clip between the two. Got about half a turn out of the bolt, so perhaps that was a bit of the problem - poor sealing, so drawing air. I also checked other bit of the system for gas-tightness... as best I could. Oxygen sensor got about a quarter turn, and the exhaust studs (which were replaced) also got about an eight to a quarter turn. Not much at all, but when I rode in this morning the exhaust system was noticably quieter, and backfires wer considerably less frequenty - and the only one I did have was more of a loud pop, that a gunshot 'bang'... Time will tell is the carbon build up comes back... Thanks for the tips!