Right or wrong

I agree, it should have run faster than that. Make sure you don't have one of those crooked tapped KB crankshafts.

Possibly the compression is leaky in this one. Try swapping the piston/cylinder set from the fast one and see what happens. Then try swapping the head. First, check and see if both engines have the same SPI gap.

Is the orifice of the NV positioned at the same angle of attack in this backplate? It should be slightly at an angle, not pointed straight towards the reed.

Does the reed move as freely during the suck-blow test in this one.

Does it needle consistently? Possibly the crankcase isn't pulling tightly enough against the backplate. You can bottom-tap the holes and use longer screws.

When I test ran the Black Widow, of the rebuild thread I wrote last month, I balanced a Cox 5x3 and bolted it up. It would not get out of the 17s. I switched to a Top Flite 5.25x4 and it ran a steady 19.3k... over and over again. I cannot explain why, but try a different prop and see what happens. Sometimes these things make no sense.

If I come up with more ideas, I'll let you know.

Most of the fuel etc are the same as last
Time. I did put a new head on but I'll
Swap that back.
No go on the other piston Rusty Co's it's got a ffffff rather
Large hole in it.
I did think the new set's spi was perhaps a little lacking
I'll compare that to another one as well.
Please keep the suggestions coming lads.

If it's a new piston/cylinder set you may want to check the ball socket. Most new pistons come with a fairly sloppy ball socket, some worse than others. When this joint gets too sloppy it makes the engine hard to start and if the engine is a high revver than the sloppy joint causes a noticable loss of power. At least this has been my experience. Your mileage may vary.

John Goddard wrote:
I did think the new set's spi was perhaps a little lacking
I'll compare that to another one as well.

You can wrap the piston in tape and lightly chuck it in your drill press. Take a sharpie while it's spinning and make a mark around the very very bottom. Hold a small file against it until the mark disappears. That will give you a half mm more gap. Sounds scary, but it works great. After you try it once, you'll have to resist the temptation to do it to others. This procedure has the official Rusty Seal of Approval. It works.

17k is decent John.
How much does the OT weigh?

RknRusty wrote:

John Goddard wrote:
I did think the new set's spi was perhaps a little lacking
I'll compare that to another one as well.

You can wrap the piston in tape and lightly chuck it in your drill press. Take a sharpie while it's spinning and make a mark around the very very bottom. Hold a small file against it until the mark disappears. That will give you a half mm more gap. Sounds scary, but it works great. After you try it once, you'll have to resist the temptation to do it to others. This procedure has the official Rusty Seal of Approval. It works.

Cheers Rusty
I took the mota apart last night and (horror of horrors) found Bernies last batch of td cylinder sets have the smallest amount of SPI I've yet seen, any less and there wouldn't be spi at all.
I'm going to 'borrow' a TD top end from one of my 'proper' TD's to see if this wakes it up.
If it does (I suspect it will as it is a VERY SMALL amount of spi) I'll get Phil '7 cylinder' to cut the pistons down, I'd just mess it up.

nitroairplane wrote:17k is decent John.
How much does the OT weigh?

You're joking Indra 17 is good for a surestart but this ain't a sure start any longer..
I forget total AUW but it was around 700g.
At 19+k it's a fun model to bumble around with, at 17 it's orrible
and a fight to keep it in the air.

Amazing the things you find out when you start to pull several engines apart at the same time....
1, TeeDee and reedie cranks aren't interchangable DOH
2, Although TD pistons are actually heavier than surestarts the killer bee
are by far and away the lightest in my collection so,-

Ladee's and Gennnllemen
I give you
The Engine Cox didn't dare make
The
KILLA B 'STARD



My Neighbours have been clammering for something like this and if this one doesn't do the business
with the OT I might have to look at a












shhhhh
Norvel

Cool John,

I like the name. I going to have to forget I heard the Norvel remark and completely dismiss thr newb remark about not knowing TD cranks are different from reedies.

Lastly, I have to give you big props for doing what you do with these engines. I enjoy watching you push the envelope!

If this doesn't make the 'Ol Timer rip up the skies then your best bet would be to douse it in petrol and roast some marshmallows.

That would be more dignified than a Norvel. Lol just kidding I like Norvel's even owned one once. I would love to get my hands on a Norvel .15........

Later John Boy!

cribbs74 wrote:Cool John,

I like the name. I going to have to forget I heard the Norvel remark and completely dismiss thr newb remark about not knowing TD cranks are different from reedies.

Lastly, I have to give you big props for doing what you do with these engines. I enjoy watching you push the envelope!

If this doesn't make the 'Ol Timer rip up the skies then your best bet would be to douse it in petrol and roast some marshmallows.

That would be more dignified than a Norvel. Lol just kidding I like Norvel's even owned one once. I would love to get my hands on a Norvel .15........

Later John Boy!

how badly do you want a norvel 15? i had one but gave it to a friend along with a surestart .049. Im pretty sure i can get the 15 back

mitchg95 wrote:

cribbs74 wrote:Cool John,

I like the name. I going to have to forget I heard the Norvel remark and completely dismiss thr newb remark about not knowing TD cranks are different from reedies.

Lastly, I have to give you big props for doing what you do with these engines. I enjoy watching you push the envelope!

If this doesn't make the 'Ol Timer rip up the skies then your best bet would be to douse it in petrol and roast some marshmallows.

That would be more dignified than a Norvel. Lol just kidding I like Norvel's even owned one once. I would love to get my hands on a Norvel .15........

Later John Boy!

how badly do you want a norvel 15? i had one but gave it to a friend along with a surestart .049. Im pretty sure i can get the 15 back

PM sent Mitch.....

cribbs74 wrote:

mitchg95 wrote:

cribbs74 wrote:Cool John,

I like the name. I going to have to forget I heard the Norvel remark and completely dismiss thr newb remark about not knowing TD cranks are different from reedies.

Lastly, I have to give you big props for doing what you do with these engines. I enjoy watching you push the envelope!

If this doesn't make the 'Ol Timer rip up the skies then your best bet would be to douse it in petrol and roast some marshmallows.

That would be more dignified than a Norvel. Lol just kidding I like Norvel's even owned one once. I would love to get my hands on a Norvel .15........

Later John Boy!

how badly do you want a norvel 15? i had one but gave it to a friend along with a surestart .049. Im pretty sure i can get the 15 back

PM sent Mitch.....

back atcha

John Goddard wrote:2, Although TD pistons are actually heavier than surestarts

I believer the TD and Surestart pistons are identical. The only different TD ones were the double tapered ones from long ago.

OK
The neighbours are fuming.........................


Crept home after a couple hours at 'work' and fired her up BOY
Boy1 she ain't a surestart so starting isn't the one or two flick affair the other one was.
but
Boy2 once out of the traps she screamed past 20k so I richened her down to a safe
'tickover' and leaned her occasionally she is new after all. The bits are all off different engines
but they are unrun.
Anyway the 'tale of the tape' on 20% Nitro, 5x3 wobblemeister prop and 2 gaskets was a brief 21.8k
I think we've woken it up but then it is completely different engine apart from the glow head....