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Post by Bronson7 on May 1, 2005 18:03:09 GMT -5
Thanks for hte tips Stew. I'll keep them in mind.
Bronson7
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Post by davedunsboro on Jan 20, 2008 4:07:07 GMT -5
I was having a read of this old thread & I'm at the wheels/brakes&ratios stage & was wondering about the 17 tooth front sprocket - 44 rear or leave the 16 & put a 42 on the rear or maybe go to a 40 if you can get . Where would I get a 40 from so I could try the experiment anyway ? the engine will be 1st oversize & I'll be running with a 36mm mikuni flatslide with a fairly straight thru exhaust system on it . what do you think ? Cheers Dave.
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Post by fenz on Jan 20, 2008 5:31:23 GMT -5
Dave what size chain are you running??? as i would think that more sprocket sizes would be available in 520 chain (xt tt) as well as the whole sprocket chain package will be lighter.
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Post by frankyb on Jan 20, 2008 16:50:28 GMT -5
Hi Dave, bike bandit in the u.s.a, have a 40 tooth rear for the 79 xt500. Being an xt it will be 520 pitch, but will fit an sr cast wheel. Cheers Franky b.
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Post by andy on Jan 21, 2008 14:06:52 GMT -5
Hi bronson, I run a 17t front sprocket so it gives 15mph/1000 revs.before i had it rebored and new piston i could achieve 85 mph without to much problem and 90 on a good day!However i've always thought 5th gear is a bit tall either at 16 or 17t.does it rev out in 4th? when my bike is run in i'm hoping for a good 90 top end.Food for thought 1 definitely unrestricted exhaust muffler,2 either raise the needle in the carb a notch or 2 or up the size of the mainjet.advance the timing a bit.remember its at full throttle where the carb needle and mainjet is at its most effective.If these tweaks dont improve things i reckon your looking at a top end job,which isnt to difficult if you take your time and properly measure the wear and tear on the piston,rings,valves,springs,camchain,rockers and especially the cam itself[this could be the problem].A good sr500 should hit 90 in standard trim without to much problem.
regards,
andy
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Post by davedunsboro on Jan 22, 2008 5:15:59 GMT -5
Interesting ,I didn't think of the brother (XT) for sprockets/chain . Fenz when you say 520 pitch as opposed to 530 does that mean the links are shorter/longer or just thinner ? And does it mean you change the whole lot ? say 18 - 40 & a new chain to suit. (reason I'm asking is I've got a brand new 530 oring chain still in the box that looks like its going to stay in the box for a while longer )Cheers Dave.
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Post by fenz on Jan 22, 2008 6:07:29 GMT -5
Dave the pitch is the same but the chain/sprockets are narrower there for the whole set up is lighter. Run a good o-ring style chain and you will find you rarely have to touch it. I run 520 x-ring chain on my yz426 dirt bike which gets ridden constantly in the dunes and only have to adjust the chain every couple of months. Look here www.gizmology.net/sprockets.htm |
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Post by caferacercarl on Jan 22, 2008 20:27:31 GMT -5
Lightly modded SR will pull 17 /40 nicely for over 200kph and approx 4000 to 4100 at 100kph from memory, [will go to the workshop today to verify] but, 18/ 40 has to have a quite strong engine to pull in top but 270 is easy, I think the English said something like this back when the Manx was king, " you need 50bhp to propell a 300pound bike at 100mph [160kph] " you can imagine what that inspired in me..............SR that beats Manx..............and it all stemmed from that. regards Carl. oh, the 18t was made as an option for the TD3 and fits with the XT,TT spacer. I think Ive started something here, better go.. Carl.
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Post by colinjay on Jan 22, 2008 20:47:21 GMT -5
Carl,
Regarding your our comment above, "50HP to propel a 300lb bike to 100mph", somewhere deep in my cloudy memory I have a figure of 34HP (or close too it) that come to mind as the HP require to get an average motorcycle to 100mph!
CJ
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Post by davedunsboro on Jan 23, 2008 6:00:23 GMT -5
Great work guys ! Once again a wealth of info at the end of my fingertips. Thanks for clearing the pitch thing up for me Aaron , I'll do that mod later(do you get gen-yammy bits or is there an aftermarket set/sets to buy) for now I've got a 17 front ,a 42 rear & a 530 non oring chain which should be OK to test with (I just spent $600 today on tyres brakes etc so I'm breaking the budjet nicely?) Oh well I've got a mine shutdown starting next week for 4 weeks straight so more funds are in the pipeline cheers Dave.
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Post by caferacercarl on Jan 24, 2008 2:09:55 GMT -5
Stock SR main in aussie was 300, needle was I think 6FL25, screw under front is fuel screw if you wind it out you get more fuel [not air] If the bike fouls plugs replace the little triangle diaphragm under the bowl and the float needle/seat set, these carbs are good and work even with heavily modded engines. regards Carl.
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Post by caferacercarl on Jan 24, 2008 2:16:29 GMT -5
Oh ,sorry colin just read the HP thing, that was a very OLD set of figures, and Dyno's ain't Dyno's mine reads very low compared to the Dyno jet type [ Andy's engine I built pulled 38hp on my machine but we all saw it murder TZ350's at Phillip Island at the international classic down the straight no less, but some machines like a shenck dyno read 61hp from my engines,clearly not possible due to the sums, a stocker in good nick with a noisy muffler pulls 17 at the rear on my Dyno Dynamics machine. regards Carl, again.
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Post by colinjay on Jan 24, 2008 16:30:49 GMT -5
Carl,
I always knew that there were differences between different makes of dyno, but I didn't think that there would be such maked differences as you have just highlighted. I would have thought somewhere around the 10% or so difference. Just goes to show that when you start developing and engine you should stick with the one dyno for testing, and as has always been the case the only real dyno is the track.
With regards to all the chain and sprocket size questions, here is how chain is measured;
The first digit in the number is the distance between pin centres in 1/8's of an inch, i.e. for the common sizes, "4" = 4/8 or 1/2", "5" = 5/8" and "6" = 6/8 or 3/4" pitch.
The second two digits in the number is the width of the roller / distance between side plates, agian in 1/8 of an inch, i.e. "2" = 2/8 or 1/4" and "3" = 3/8".
So, a 520 chain is a 5/8" x 1/4" chain (5/8" pitch, 1/4" width) and a 530 is a 5/8" x 3/8" chain (5/8" pitch, 3/8" wide).
An yes all chain is still measured in imperial sizes, there are some odd sizes like 428 and 625 that don't quite translate to the general rule above but thay are not that common on bikes now days.
CJ
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Post by fenz on Jan 24, 2008 18:41:04 GMT -5
Dave dont know about sprocket sets maybee Hanks eng. in QLD may have some thing??
I usually buy non genuine (last 17T got from fleabay for about $20)
Chain i normally run D.I.D o-ring but i am sure there are others out there just as good.
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Post by caferacercarl on Jan 30, 2008 2:26:08 GMT -5
Australian SR's generally had a 300 main jet, [310/320 for noisy muffler/pod filter] and a 6FL25 needle I think, [will check this] [lift at least a clip as above] and work well and do not wear out anywhere near as quick as other carbs, and will support a 70% gain at the rear engine beautifully, if throwing the stock SR carbs out, send them to me and I will pay for them!! regards as always, Carl.
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