eddiethefish

Thought STS S5 Dragon comes with extra conrod, check.

V1RR

From what I heard, you have to pay around $15 USD for a replacement. the rod should be strong enough, only the bushing within the rod make me worry.

smartdriver

Well,I broke my Dragon in as per the sheet and had my first race with it and now the conrod is worn out and the piston has some ugly discolorations in one spot on the sleeve.My engine didnt come with an extra rod

so I guess I have to buy another one.....
By the way Im not some kid who doesnt know what he is doing.
not happy at all......Guess I need to stick with Novarossi based stuff....

Manticore

I broke in the D5 "NOT" according to the instruction. I kept the engine running "Very" rich for 1 litre on starter box. and another litre on the track with "Very" rich needle setting. and i start to lean the engine progressively. I inspected the conrod after the day and the conrod holds up perfectly. I finished 1 gallon of fuel and inspect the engine again and the conrod still hold up nicely and it is still difficult to remove the conrod/piston from the crankpin for rebuild.

It does happen to novarossi based engine on bad conrod. that is why the conrod has a copper busing there and this is the purpose to protect the crankpin. JMHO

rodrigo1508

so you sugest to change the conrod after the break in of the D5?

Fisher890

So 20 tanks for break in?If its just the Bushing that has the issue is there a way to replace the bushing instead?I was ready to Buy a dragon but they are starting to sound like just another wannabe.Correct me please if I am wrong but they have a 7 and a 7.5 mm crank when all the other nova based motors went to 11 and 11.5 mm Cranks. Is this why they eat bushings?I'm not looking to bash the motor just want to know what I might Have to face since I was Heavily in favor of Buying it in the next day or so and if I need to Buy an addition conrod I'd like to include that in my order. Or if its just gonna eat a rod per gallon I'll stick with my RB's and spend the $$ to start.*&%*&)()*(W*&) Choosing 1 affordable Motor SUX!

smartdriver

Manti,I dont think that my engine should have worn a rod out like it did.
It didnt have ANYTHING to do with the break in process.
I got a bad one and you didnt.
I need to get in touch with Dino and see what I can do.

edwintam

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edwintam

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InitialD

It's not another wannabe. It's a good engine. Just that during breaking in (depending on how you do it), the conrods do not last. A Nova conrod would be a good replacement. Once the engine is broken in properly, there should not be any problems with the conrod when run correctly.

As for the crankshaft diameter, I may be wrong but I think you misunderstood the dimensions. I believe the Dragon's have 12 mm diameter crankshaft at the inner side while the shaft at the outer side tapers to 7 or 7.5 mm which is somewhat similar to the Novas. I also do not think that this leads to broken conrods. More like broken crankshafts if indeed the crankshaft was 7 or 7.5 mm all around...

I may be wrong but I think the STS RS3 (older model) that I currently have is already having 12 mm in the middle of the crankshaft and 7 mm diameter at where the flywheel is installed.

prawntoe

You are right on the RS3 crankshaft dimensions - 12mm/7mm.
Nova based are 11mm/7mm. NS-based is 11.5mm/7mm.

Dragon crankahfts have similar measurements (12mm/7.5mm-D5 and 7mm-D3) but spot a new crankshaft design that's different from STS RS engines - more similar to Sirio.

stefan

The D5 has a crank bore of 7.5mm and the D3 has a legal 7 mm bore, just like all ROAR legal engines must have.

This is not the outside diameter!!

stefan

I have not seen smart drivers conrod after last weekend, so I cannot comment on that, but what I can say is, that I was not very impressed with the power it made.

I'm used to fast modifieds like Murnan's and my own ones and the D5 felt rather average on the track.

I drove smarty's car in the main (because the whimp had a headache ) and wasn't impressed at all.

We were both thinking about replacing the 6.5 mm carb with a 5.5mm Nova Rossi carb.

I'm going to brak in my D3 soon and I will watch the rod closely and report.

InitialD

Thanks for the info prawntoe. You're the STS engine expert !

Ummm, the front end bearing (and hence crankshaft) of the D5 and D3 are not interchangeable then?

prawntoe

internal dimension of the bore is different (outlaw vs legal) but external dimension of RS/D3/D5 are the same, thus they are interchangeable.

12mm ID bearings (internal) are ISO standard, therefore can be replaced with standard bearings. . .

front bearings should be the same and interchangeable with Nova based engines.