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stock bore size and a shell #1
- Thread starter ExtraRegularGuy
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- cam performance shell cam shell#1
ExtraRegularGuy
XS650 Enthusiast
Pre jetted carbs would be nice, but those would be just under half of my budget for the engine build itself. Ill keep an eye out on ebay for a set of proper used mikunis, jet it to the recommended baseline, and tune it. I was thinking that I would route the pipes in a very similar fashion to how they run stock, I've read somewhere that 33 inches was a good length, but I will also try 29. I don't think cops really give a damn as long as I'm not stunting in a parking lot or some nonsense like that. Griz, those aren't only great engine building tips. That is rock solid life advice, and I agree with every bit of what you said.
ExtraRegularGuy
XS650 Enthusiast
I may take you up on that offer, funding for this project will come in next month and I will let you know as soon as possible
When out there looking for used check the Needle and Needle Jet..I like 6dp1 needle and 159 P5 Needle jet, some like 6f9 and 159 p6 ,there are of course other combo's but to replace these is about $38.00 or so, not to mention the pilot and mains. Be sure when buying used ask what size the slide are in there also , they run about $38.00 each new. I like 2 or 2.5 , Gary
ExtraRegularGuy
XS650 Enthusiast
thank you very much for the advice, i have a lead on a set of VM carbs a guy was running on his triumph 650. I think it is safe to assume that those would be a safe carb to use
ERG, before you buy VM34's, here's the range of stuff you'll need to dial in a cammed 650. The fewer of these things you find in the carbs, the more expensive the final product becomes.
Slide: 2.5. NJ: P5 or P6. Either will work, I prefer the P5. Needle: 6F9. I've used the 6DP1, which is the generic item; but in rolloff testing it gave me a lean surge at 7/8 and a rich sputter at 3/4. You might have better luck. PJ: 22.5 and 25. MJ: 175 and 180. AJ: open hole; remove if present.
As Gary says, assume nothing. If the seller can't or won't give you specs, you're rolling the dice.
Slide: 2.5. NJ: P5 or P6. Either will work, I prefer the P5. Needle: 6F9. I've used the 6DP1, which is the generic item; but in rolloff testing it gave me a lean surge at 7/8 and a rich sputter at 3/4. You might have better luck. PJ: 22.5 and 25. MJ: 175 and 180. AJ: open hole; remove if present.
As Gary says, assume nothing. If the seller can't or won't give you specs, you're rolling the dice.
ExtraRegularGuy
XS650 Enthusiast
right right, i am awaiting correspondence from the seller as we speak. If it close to that jetting i may make out like a bandit on these carbs
Yep, didn't detect any flat spots, etc. rolling on the throttle, but the only test instrument I applied was the seat of my pants; the defects only showed up rolling off from WOT, and cleared up with 6F9's.
Tried that today, nothing. smooth all the way from to bottom and top to bottom, I can set it anywhere and will hold a constant rpm in any range For your rolling off from wot , you have vacuum still pulling hard, sure it wasn't a dirty slide and can cleaned up when you replaced the needle. Which will make it slow reacting.
Pretty sure that wasn't it; wouldn't explain getting a lean surge at 7/8 and fat sputter at 3/4, and I left the 6DP1 needles in place for quite a while double checking ignition, etc. The motor felt fine at 3/4 and 7/8 rolling the throttle open. I'd be more inclined to think that differences in exhaust systems, porting, etc. gave us different results. Almost forgot another factor--the motor those carbies were on had 77.5 mm. Venolia pistons and cc'd out to a tad north of 10:1.
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ExtraRegularGuy
XS650 Enthusiast
i have been searching for stock piston ring land dimensions and havent found anything. I mostly find data on 80mm and 77mm pistons. Being that those are aftermarket and have a shorter axial height that information isnt really relevant to my build. Does anyone have a stock XS piston that they would be willing to measure for me?
I'll see what I can excavate from the stash, but I need to know a couple of things. First: what year is your motor? Second: what dimension are you looking for--top of compression ring to crown? Groove widths? Land thicknesses?
ExtraRegularGuy
XS650 Enthusiast
ive got an 81 engine, im looking for ring land height and depth. I think i can source the dimensions of stock rings from the depths of the form. Im able to get a discount on total seal rings and im going to have to piece together a set ring by ring
I'll measure some stock rings and save you some effort.
ExtraRegularGuy
XS650 Enthusiast
Griz, you are an angel
Here's what the mike and caliper had to say after a check of 3 samples.
Compression ring (top): Th: .046". W: .117".
Scraper ring (middle): Th: .0585". W: .143"
Oil ring (bottom): Th (total for 3-piece assembly): .150". W: .117"
If you're using Total Seal rings, you might want to send a piston to the vendor for sizing.
Compression ring (top): Th: .046". W: .117".
Scraper ring (middle): Th: .0585". W: .143"
Oil ring (bottom): Th (total for 3-piece assembly): .150". W: .117"
If you're using Total Seal rings, you might want to send a piston to the vendor for sizing.
ExtraRegularGuy
XS650 Enthusiast
thats not a bad idea on the pistons, i am tempted to order a pack of the honda rings every one seems to use and compare measurements. If the sizes match then lll have a much easier chance getting exactly the ring pack I want. Also, i think i figured out how to i should make my adjustable cam gear setup. If it works out well, it will only cost me whatever aluminum round stock is at the time....or a couple of cam gears. We will see. Thanks a ton for taking the measurements for me griz
Griz, thanx for taking the time to get these measurements. I've copied your posting for future reference. The manuals don't show the ringland depths, here's an excerpt:
