Thread: Slower Speed!!! Oh NOOOO
10-25-2009, 09:04 PM #1
Free Flow Exhaust= Slower Speeds???? please help
I just added a free flow exhaust to my 08fxho cruiser, current mods solas 14/20 impellor, riva velocity stack, riva power filter, pump seal kit, and intake grate and was doing 63.2 ( i know its not as fast as a sho or fzr's but it moves fast enough for me and get me places lol) on gps and i took the ski out today to test it to see if I would have any speed gains and the best I got was 59.9.... Does the free flow exhaust make you lose top end speen??? Because it seemed like it happen to me.
Did about 6-8 passes and best speed was 59.9
Last edited by fxho; 10-26-2009 at 08:40 PM. Reason: different tittle
10-26-2009, 05:13 AM #2
I'm in the same boat and my list of mods is as big as the next guy. If there is one thing I'm learning it's this:
1. You need before and after RPM's via a on board tach.....if your motor isnt able to get to the go fast RPM's due to being over propped or what have you speed will decrease.
2. Just adding parts all at once makes it very difficult to find out what is "holding you back". Put the stock prop on would be a start. I'm no expert and others will chime in but if you aint banging the limiter the prop should not change. Just adding exhaust on a two stroke makes huge leaps and bounds but on these four strokes I can't see that kind of speed loss from helping it breath better. Strange!
10-26-2009, 05:46 AM #3
check ur pump shoe and ride plate are sitting higher than the hull and not causing draggggg
10-26-2009, 08:43 PM #4
Does the free flow exhaust make you lose speed at top end??
10-27-2009, 05:00 AM #5
coming more from a 2 stroke back ground the free flow usually loose very little rpms with maybe a spped loss of .5 to 1mph.
In you case its much bigger speed loss have you try putting back to stock for to see what happens
10-27-2009, 05:14 AM #6
- Join Date
- Oct 2008
- Glasgow, U.K.
Assuming that water conditons and the amount of fuel you were carrying were similar on both days, I can't see how fitting a free breathing exhaust could cause your dramatic speed loss.
Did you notice what your maximum revs were on both days ? If they were the same, then your speed loss must be due to an environmental change.
With Riva stacks and filter, my 2007 fxho revs out at 10,300 ( I think, because it gets a bit blurry )
10-27-2009, 10:21 AM #7
I don't think a free-flow would cause a speed loss on a high-revving 4-stroke like that. And even if it did, 3mph is a lot!
I'd double check the grate, shoe and plate like others have said. Make sure they aren't sagging or crooked. Also make sure there isn't anything stuck in the pump or wrapped around the driveshaft.
I'm not sure how the rev limit works on the HO motor, but if everything else checks out, maybe you're banging the rev limiter with the FF? You should check your RPMs.
10-27-2009, 09:41 PM #8
10-27-2009, 09:44 PM #9
10-27-2009, 09:46 PM #10
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