tyhatts

Picked up a couple 454 engines yesterday used. One is a bump start model and the other is a pull start model.

The pull start 454 looks to be in good shape, but the guy over tightened a bolt in the end of the crank shaft and broke it off? Im going to try and save myself $60 and drill out the broken peice. But Im not very optimistic.




Piston and sleeve




I need to get a carb for this engine aswell, What is the differnce between the 9.5mm carb and the 8mm ??? ( other then 1.5mm lol !! )

Thanks for any help

Ttowntoolman

Cant you just swap cranks? I think they are both the same, one engine just has a backplate for bump start. That is how the LRP .28 spec 3 is. Anyhow good luck drilling out the broken screw.....looks like someone attempted this before. If you can, put a left hand drill to work on this project and hope it grabs the screw while you are drilling. I have used this method many times with good outcome. I am not sure about different carbs although there are usually different venturi inserts for the carb on some engines and they are usually described as a 9mm insert or an 8.5mm insert.

1QwkSport2.5r

A bumpstart crankshaft will not have the extra little "nub" on the crankpin for the one-way clutch to grab for a pullstart or spinstart to work. You can see the crankpin extension in pic above that the one-way clutch grabs onto. A bumpstart crank wont have that extension. I'd be awfully surprised if it did.

+1 on LH drill bits. I had to do this on a broken alternator bolt in my Chev 350 in my S-10. Left hand drill grabbed the bolt, spun it right out. The bolt was broke off flush with the surface of the mounting flange. If the bolt/bolt hole is already mangled, plan on getting a new crank because the chances of getting that broken bolt out are nil.

If that doesnt work, find a crank from an *bay chop-shop. I'm sure you could find one cheaper than you could get from Horizon/Losi/Dynamite. OR get a crank for a SH .28 pullstart. P6 or P8 should have the same crank.

HerrSavage

Also, don't forget - Losi 454's go brand-spanking new for as little as $100 on ebay... (I would never spend 60 bucks on a new crank when the whole engine can be had for 40 bucks more..)

Generally speaking, smaller carb venturis make the engines more punchy down low, and increase run time..

johndavis

the left handed drill bit is the best way. if it will not turn put a little heat to it. most people use locktite on that screw. the heat will release the locktite

tyhatts

Yes... Thanks for the tips guys 

1QwkSport2.5r

Heat the crankcase with a hair dryer. You could put the liner in the freezer as well.

Ttowntoolman

I agree with you as this is usually the case. I have a LRP .28 spec 3 that I got with a pull start (used) and I purchased a backplate for it to make it bump only. The backplate is cutout on these things to fit the crank nub. I also bought new a Dynamite .26 mach 2 for my son. This came as pullstart and I got a backplate for it also, same deal, crank pin fits into groove in backplate.

Maybe because I always had pull start engines and changed them to bump, they have the extra nub on the crank. Maybe they sell bump only engines and the nub is gone?

HerrSavage

That is correct. That was definitely the case with the LRP Spec 3. There were two versions. The "Truggy" version did not have the nub. This used to come up in MT forums occastionally: some guy had bought the Truggy version of the Spec 3 by accident, and would ask about making it pullstart. No nub - no dice...

I assume the current Losi 454's are the same: the 454 in the XXL will have the nub, the 454 in the 8T 2.0 won't.. I assume that's the case..

The DYN0960 backplate btw fits all the LRP Spec 3's, Mach 427's, etc.. - all the SH-based engines .26-.28...

1QwkSport2.5r

I wonder if the backplate part numbers for a bump start engine and a pullstart conversion to bump start are the same part numbers. I'd heard some engines converted from PS to BS have the special backplate mentioned above available, but I doubt all engine manufacturers do this.

I'd entertain the OP to post a pic of the crank from the BS engine to compare.

purenitro33

You could always cut the shaft back to the threads and use something like this.

http://www3.towerhobbies.com/cgi-bin...?&I=LXABA2&P=7