True Impeller Size?

[exoh_e]

Hi,

I have two impellers in my Challenger that I believe are very worn, almost nearly 138mm. I just bought two reman'd impellers trying to "save money" and they were roughly 139.2-5mm. If I were to buy a brand new impeller would it be exactly around 140mm? Thanks!

Roughly I spent 240 for two. They are "tight" but if you were me would you just go and get the new ones or f-it and keep these.

 

[RockyImminence]

Spec (at least as I remember) is 1mm of clearance before you start having cavitation issues. Just remember that even a new impeller is going to vibrate and groove the wear ring, so I think you'll be fine. The impeller on my 96 SPX is beat to death but with a new wear ring it's run awesome the last two seasons.

 

[etemplet]

Hi,

I have two impellers in my Challenger that I believe are very worn, almost nearly 138mm. I just bought two reman'd impellers trying to "save money" and they were roughly 139.2-5mm. If I were to buy a brand new impeller would it be exactly around 140mm? Thanks!

Roughly I spent 240 for two. They are "tight" but if you were me would you just go and get the new ones or f-it and keep these.

Nope, no new impellers. How is the performance? Top speed? Out of the hole?

As @RockyImminence stated (1mm) clearance is fine. I'd have to have a pretty large gap and a performance issue and I'd never buy new anything. LOL Fix the old stuff. Good Luck !!

 

[exoh_e]

Not the best, last year I was running 45-47 mph tops. This year I was getting 42-44. It's a 14.5 twin 720. I expected atleast 49-50. Carbs are "brand new" I didn't feel like rebuilding them like for the other skis I have.

I siliconed the ride plates, I have neoprene seals, almost positive the carbs are "opening all the way up" at max throttle. 24 ft lb torqued in. I'll double check the carbon seals but... not really suspect because the hole shot's okay. hmmm....

after I install the new impellers; i'll try new plugs and verify the gas is good. (I did drain it last winter and added more this spring). I even installed 139.5mm wear-rings because I felt like my impellers were worn. I did buy the white delrin wearrings from osd this year but haven't installed them. I just installed the 139.5 mm wear rings this spring.

 

[RockyImminence]

You could always check compression too. Older engines wearing out could be the cause of your speed loss. I'd be curious to hear other's takes but I'd trust the factory carbs with an OSD back to OEM rebuild kit over anything else "new" or otherwise.

 

[etemplet]

You could always check compression too. Older engines wearing out could be the cause of your speed loss. I'd be curious to hear other's takes but I'd trust the factory carbs with an OSD back to OEM rebuild kit over anything else "new" or otherwise.

Yes indeed. With the carbs as long as they are clean and the nozzles in the throat are spraying strong. I've only replaced one carb having restored about 20 jet skis. LOL

 

[exoh_e]

Nope, no new impellers. How is the performance? Top speed? Out of the hole?

As @RockyImminence stated (1mm) clearance is fine. I'd have to have a pretty large gap and a performance issue and I'd never buy new anything. LOL Fix the old stuff. Good Luck !!

Top Speed is 44, New wear-rings, siliconed ride plate, Neoprene seal, "tight clearances" on the impellers, the carbon seals are tight... Brand new single carbs on each engine. 137 psi even on all sides. I feel like last year I was getting 46-7. So confusing... 25 Gallons of fresh fuel. New plugs. Hole shot is pretty good only cavitates for let's say one second. brs8e

Only weird thing I havent really looked but the exhaust seems to be connected in a really strange way, I expected them to just be directly out to the boat. It seems they're connected to one another some how.I cant find a manual for 99 speedsters (I have a 14.5 2000 challenger with twin 720's which is the same think) without having to pay 15 dollars...

 

[etemplet]

1996 Speedster I just restored ran 52mph with rebuilt engines. A few more hours of run time should loosen them up a bit for a couple more MPH. Twin 720's. I'd look at engine RPM as an indicator. Check the internal condition of your exhaust hoses..

 

[exoh_e]

You inspired me. I was like man; I want these wear-rings to be TIGHT! I had some 139.5 undersized wear-rings, and was like whatever let's throw the white delrins I bought from osd and never put in(There's definitely more gap in the impellers but I guess it's totally fine.). Running at like 47 again. Woohoo!

Note, Actually I am editing this after. I did have some set-screws in the other wear-ring I think was causing it to "Drag" more than it should I removed them and just used red loctite.