Gidday All,

I have an 05 FXDX and I am going to replace my stock 70 tooth rear pulley with a 68 tooth pulley. Will I need a shorter drive belt? I believe the standard belt has 133 teeth. I will be using a 32 tooth transmission pulley.

If I were to run a 33 tooth trans pulley would a 133 tooth belt be suitable? If not what length?

Is there a web site where this type of information is available?

Thanks, Tux

 G'day Jack,

I have a similar build to yours mate but mines a 99 model and I have been thinking of converting to a 1 1/8" belt to help fit a 150 tyre ( so the tyre looks wider than the belt ha ha ) and lowering the revs for better country road cruising, the gearing is too low for country roads for a worked donk but great around town. Would like to go the 6 speed conversion but the price kills that idea so I have been thinking of going down the same path as you but with a 34 S & S tooth front sprocket  with a 70 1 1/8"  rear sprocket and that would give it a 6% increase in the gearing according to S & S site. Been talking to a bloke in America and he seems to think that the best belt strength wise is to go the 1" 137 tooth belt that fits a 2008 Electraglide Std FLHT and turn 1/8" off the rear pulley if I want to.

So if you went 33 tooth on the front and used a 135 tooth belt and you sill had to make a 3/8" adjustment to the slots in the swing arm and further adjustments to the other parts I take it that I would have to do the same even though I am going to use a 34 T sprocket and 137 T  belt. 

• Do the mods that you done to the swing and adjuster blocks need to be done at a shop and do have some photos.
• What have you done to correct the speedo readings.
• What size tyre do you run.
• Could you take a measurement of the narrowest point of the inside of ya rear guard for me.

 

If it requires to much butchering of the swing arm I might just say "fuck it" and stick with the stock gearing since I got it dyno'ed I am getting 46 - 49 mpg now but will still change to a 1 1/8" belt so I can fit 150 tyre

 

It's tough to advise, not really knowing if a 99 and 02 are the same. The thinner belt with your engine setup ( my opinion) may not hold up if you hit the throttle hard. I broke my stock belt when I power shifted from 1st to 2nd., prompting me to make the change. If you were to go to the 34 and the 135 belt you would be in the stock setup position for the rear adjustment. As for the mods, if you have a high speed grinder, air powered, you could lengthen the slot as I did with a carbide cutter on it, or you could use a rat tail file and take alot of time doing it. and the adjuster blocks, I just ground mine shorter with a bench grinder till they were short enough to pull the belt that extra 3/8. My bike came with the 150x80x16 so that was the only change I made back there. Too many guys think they know shit and give bogus info and it pisses me off knowing someone is going to screw up their ride because of it, so I don't comment unless I know what i'm saying is good info. 33 and 70 with a 135 belt is what I did, so, your 34 and 70 with a 137 belt means you would need to take that slot another tooths worth, that might be too much for your swingarm to handle and your wheel base would be another 3/8 longer and the tire may hit the back of the fender,not sure of that but it's something to think about. How close is your stock belt to the tire now and what size is your tire? Other than looks, what do you expect to gain with a bigger tire? If your tire is a 140, the difference would be almost unnoticeable, perhaps a different brand tire would fit without changing the belt width(I don't know, maybe?) Go to the hd forum (HDTALKING) usa and ask what they think, there are some pretty knowledgeable dudes on there. Look at their status, "road warrior" "senior rider" "legend" and see how many post they have before going with the info you get there. I hope I helped some but not knowing your particular scoot, I'm just talking trash until you can confirm the info. I do know that a 34 front sprocket will change your cruising rpms quite a bit and will definitley be noticeable, my 33 made plenty of difference without robbing my low end punch, I lost a little holeshot punch but that seems to be the only noticeable area and not being a racer anymore, I don't care. The cruise is where I'm at and I'm quite happy with that. 80 on the freeway is really nice now and cruising at 55 still gives me good twist power to pass without downshifting.-----jack--- forgot to mention, my speedo was off to begin with so the 1 tooth made it read right now, but 2 would have gone too far and made it read too slow for the actual speed. I checked it with a radar that displays your speed (without the cop)

 Jack,

Thanks for ya honesty and I tend to agree with ya thoughts about some of the so called experts who try to blind us with their bullshit number quoting and how much they have spent to trying to turn their  pigs ear into a silk purse. Although I am inclined to wounder as to why your belt would have snapped during power shifting manoeuvre, loose belts tend to snap more than overtightened belts so the story goes, and also ya must have a good box not to hit neutral. Also I don't think the belt width is any indication on the strength, just look at some of the big boar kits that Harley put out without recommending a belt upgrade.

My old girl is putting out 86 hp and 91 ft lbs at the back wheel and I hope to go to a wider tyre for 2 reasons one is for a bigger contact patch that will help with better dry grip and tyre mileage and the other is to fill out the rear guard. At the moment I have a Avon 130 on and they are the same as the stock Dunlop width wise but I had been running Metzelers in the 140 size and all the tyres that I have used have have a clearance of about 1/8" from the tyre to the belt, the tyre shop even said that the Metzeler width sizing is narrower that the others and the difference between a 130 and a 150 is 20mm or 10mm each side. And from what I can gather from what I have seen the only real differences between the 99 to 05 arse ends is the mount for the 2 pot brake and the 1 1/8" belt and pulley on the 00 and up models, some big changers occurred with the 06 different gear box interface and the 1" belt but I can be corrected if someone out there is more in-tuned with model changes that me.

Have spoke to some shops but the are very cagey about handing out any info to blokes who want to understand the workings of their bikes and do their own work but are only all to happy to get you to bring into the shop. Maybe the 34 and the 135 belt would be the way to go to reduce revs at cruising speeds and if it takes to much out of the motor I could always go the 97" build with 102 hp and 110 ft lbs at the rear to pep it up a bit.

With about 70k on that belt, I wound out in first, hard, and grabbed 2nd and hit, I thought, neutral, glad of the rev limiter, tried again, nothing and again, then heard a whirring sound and looked down and saw the belt dragging along behind. First time in 96k that I had to get a tow. the first belt got punctured by a rock. The belt tension was right though. When a belt is too loose it tends to set up a vibe, at least mine did and caused a vibe that cracked my seat mount, so I've been pretty conscious of it since. You may be right about the belt width and newer construction methods may make the belts tougher. I looked at my belt and it was definitely pulled apart as there were no signs of previous damage in the areas adjacent to the seperation. There must be something different between our bike because I have a good 1/4" from the 150 tire to the belt. I had an Avon cobra on there once and it worked great but wore out in 6500 miles so I went back to the dunlop because of the miles I put on the bike. I do have the 90x90 Avon on the front as it lasts good and sticks good. Some say not to run different brands but I run what works best for me and this combo makes me quite happy, having been a racer in years past ( a lot of years past) I'm going on 63. I think you could run the 34 tooth and get away with it but you will definitely lose the around town punch. I went with the 33 because I wanted to keep the punch and still not wind it too tight while cruising and it does that pretty nicely. My buddy put in the six speed on his ultra and couldn't pull 6th while crusing so he went to the stroker and 95" pistons making his a 103 with the 211 cams and now he can pull it fine. I used to beat him when he was by himself and I was 2 up but after his mods he beat me, but not by much, so I went to the 95 and cams, he can't beat me now ha ha.-----jack