New belt = power loss

S

sledneck1986

New member
Joined
Dec 24, 2013
Messages
17
Location
Québec, Canada
Well engine is running good. Everything worked really good. Until the Vbelt blew. So I removed all the junk that was around the primary and put on a new Yamaha 8dn-17641-01 belt. I don't know what was the old belt. Now I have the feeling that the new belt is slipping. The sled feels slower now. At cruising speeds the engine screams now. It was almost sleeping before. I'm pretty sure I've lost top speed too. The RPM's seems to rev quicker, but the sled don't pulls as hard. I checked the height of the belt in the secondary sheave and it was too high, like 3mm above. I removed the shims behind the adjusting bolts and now it's on the 1.5mm spec. But still an annoying free reving feeling. Feels a bit like if the gearing was shorter. Why an old, about to blow belt was making this sled faster than a new belt? I've read a post about different belts and that some people had issues with them. Maybe it's my case. Also I didn't wash the belt, is this step really important? How long for a new belt to ``break in`` ?


Thank you
 
You probably had an aftermarket belt which is softer than the Yamaha belt. The yamaha belt is known to be a performance sacrifice, a great spare but that's about it.
 
I know exactly what your talking about. When the 01 belt came out as a replacement belt for the original, I was told it was exactly the same, just a different part #. Hogwash, my sled started doing what you described. Cruising down the trail before the new belt , rpm would be around 5k, now it's 5600-5700. That was my only complaint about them, sled still performed great, , same wot pull and speed, and rpm stuck at 8400 all day. Just cruising speed rpm was much higher. In 17 yrs, I've been thru maybe 8-9 belts with this sled, the last 3 were the 01's, all replaced from wear, I've never blown a belt.
 
Last edited:
you need first to scuff your clutch sheaves with a scratch pad. that belt needs to be broke in. i really believe a good used works better than a new one. 3:16 (YAMMIE TONY)
 
You have to tune your clutches for the belt you are going to use. The durometer (hardness of the rubber) is different on the 8DN (harder) then it is on other belts. The 8DN requires more side pressure than say an Ultimax. I respectfully disagree with the 8DN being a performance sacrificer. This might be true in a specific situation, but tuned properly the 8DN can perform just as well as other belts. I think many simply fail to tune properly. That said the -01 belts do seem to be different for some reason. There was a change in which factory makes the belts for Yamaha and my personal feeling is that there was some unintended change involved, but I have nothing to prove this theory.

The advice about scrubbing the clutches is good, also wash the belt (mild soap and water) before first use to get some of the leftover residue and any oil from hands off the surface.

Another thing that comes to mind is that you may want to pull your clutches apart and carefully inspect them. There can be cords in where you can't see them unless you tear them apart. Or there can even be damage from the belt blowing.
 
X2 on the belt needing to be broke in. i put a new belt on my 01 SRX at the beginning of this year, and the more i rode, i would notice the tach would slowly start to reach higher RPM, until i got the normal RPM. just run it!
 
they are great belts, put a new 8dn in my sxr and it runs fine. clutches run cool, so no slipping for me.
 
Clutches and belt cleaned.......... brake in period of at least 50-75 miles,,,,(baby first 10 miles, not over 7 grand) ( YES HARD ) after that very rpms.. (under 8 grand) with out WOT till it's BROKE IN.. I know its hard,,,, you can open it up after 35-40 miles for short period of time (10 SEC)..... or so.. In the long run this will give you the best belt life..............With grip........
 
Thanks a lot for the quick replies. Finally with some ``break in`` time the Yamaha belt is doing good now. I removed the glazing on the clutches with fine sandpaper, then cleaned the clutches with brake cleaner. That seemed to help. I needed a spare belt and ordered a Dayco that I washed in a bath of hot water and soap. Thanks again, the sled is running strong now! Goodbye
 
We only run the 8dn. We usually see at least 2k miles out of each belt. Keep the clutches aligned and clean. Never get antifreeze on the clutch or belts. The 8dn is the longest lasting belt made.
 
You must log in or register to reply here.


Back
Top