energyman

My Feedback: (2)

SpeedRacer,

I feel the same way about the 10mm carbs. I like 'em...the one that works. I don't know if I just got hold of a bad batch. If I did not have one that works as it should, I would have given it up and asked them to trade for the 8mm. However, whenever I take one of the 60's and tach with the 8mm and then the 10mm back to back, I usually get a higher static reading with the 10mm. I have used the Jett Stream, Mac's header and pipe, Rossi muffler, Rossi minipipe, bolt on TT muffler, etc. onvarious Rossi's. The fact that one carb works keeps me hoping to get them all corrected, otherwise as mentioned I would have opted out for the 8mm.

I had the red jet carb off my SJ 50 this afternoon and tried to fit it to the Rossi. They both have 16mm necks but the Jett is oversized just enough to not fit into the Rossi. Polishing would probably get it to fit. This is an 8.5mm carb. Might be another option if needed. I don't know what Dub sells the carbs for.

Jim,

I have an old blackhead that is a shortstroke and another that is not a blackhead but is a shortstroke as well. They are both ringed engines. I believe the current Rossi's have a silver head on the 40 and 60's, black head on the 45, and a red head on the 53. I believe this has changed through the years.

Most if not all the older Rossi carbs were 8mm and hadtwo part HS needles.

Dave

The 10mm carb that functions correctly is getting more than adequate pressure with the Jett Stream to run overly rich. There is no fuel draw issue with this carburetor. The correct setting uses one half of the useable threads on theHS needle. The engine has been on two planes with very consistant operation. The only condition where the engine cannot be richened enough is with the carbs that cannot be adjusted properly and the idle needle has to be closed completely.

I hope Rossi's solution works. I will keep everyone posted.

Danny

RCER88

My Feedback: (25)

I dropped a Rossi 60 side exhaust in a P8 with a tuned pipe. It balanced well and flew great. I run FAI fuel in my Rossi's.

Dave Harmon

Danny.....that would be great if you would post the results....this had been an ongoing problem for decades that needs to be fixed....or at least the cause to be found so owners could fix it.
I'm not comfident that Rossi is interested enough to fix it during mfgr or they would have done it way before now.

Quikturn

My Feedback: (12)

Hello everyone,

I'm new to Rossi engines and I'm wondering if these engine should have a pinch near the top like other ABC engines have?

I have a 46 RAL which (supposedly) has about a gallons run through it and it has no pinch when flipping the engine over w/o a glow plug. The engine does have great compression and runs great too! I recently purchased a 45 blackhead which the previous owner said he ran it about 20 minutes. He couldn't get it to run right (inverted) and gave up on it. I personally haven't run it yet but after I inspected and oiled it I noticed it also has no pinch which makes me wonder if this is normal.

By the way, I upgraded the 8mm carb to the 10mm carb on the 46 RAL and noticed about a 1k rpm increase on the test bench with no problems as mentioned above.

airraptor

My Feedback: (66)

That rossi 60SE with Jett pipe seems down on power. My OS 65 AX at 22 ounces will spin that APC 11x7 at 13,800-13,900 mounted in the plane.

energyman

My Feedback: (2)

Airraptor,

Attached is a picture taken on Wednesday afternoon with the temperatore in the low 80's. Fuel was Omega FAI, APC 11x7, 10mm Carb. Sometime, as in the picture in post #4, the peak varies. Don't know why; phases of the moon, humidity, new haircut, etc. I have two of these engines. 24.4mm stroke, 22.7mm bore measured. The Jett Stream is theJS-90 version with 42mm spacing requiring no engine adaptor for the Rossi.

Danny

energyman

My Feedback: (2)

Quikturn,

The way I check my abc type engines is to remove the glow plug and turn the engine over slowly by hand with no prop. This will usually indicate if you have pinch left. I have found that the more run time on the engine, the static pinch will be less, but the compression seems to remain good.

Danny

BullardRM

My Feedback: (39)

Just spoke with Dub and you are correct. He is making the 60 in the samll case only. So my question is, what is the advantage for the block (case) size that would make the Rossi the only choice?

Jim Oliver

My Feedback: (1)

The small case (.46 size, according to Dub) has a shorter crank throw, which means less torque, which limits the small case engine to lighter props (less prop load) than the big block engines.

That said, there are some of the smaller, lighter Classic pattern models than can use the small case 60 very well. The original Kaos, Super Fli and others of that size and weight are better powered with the small case 60 than the much heavier big block 60. Be aware that an 11x7 prop is a heavy load for those engines.

Years ago, folks trimmed props to 10 1/2 dia. and maybe slightly shorter, to get the rpm & flying speed desired, when using the early smaller, lighter 60 size engines.

Just match the engine to the airframe and all will be OK.

Jim

BullardRM

My Feedback: (39)

Thought that may be the case. Looks like Rossi is in my future (again). Thanks for the reply.

Quikturn

My Feedback: (12)

That's how I check them too but was surprised to find little or no pinch although compression is excellent on both engines.

Dave Harmon

Danny....on those carbs as above, you might make a test....mount the carb in the usual way, install a pressure nipple in one of the backplate holes.
Then pinch off the carb fuel line, rotate the intake to be open, open the throttle wide, put your thumb over the intake, squirt something soapy on the carb and around the pinch bolt, then pressurize the crankcase and watch for bubbles.
I have suspected all along even way back that these carbs that have problems have a constant airleak.
Like you, I had 5 or 6 of those carbs that I simply could not make useable....but...I had 2 that did.
I got so pissed one time because of all the time and money wasted messing with these carbs...I was driving down a dirt road and threw them all out in a farmers field.
I almost never thought of them again until this discussion.

skooterII

I know this is a little off subject but i am looking at getting a rossi 45 with the vp mod 197r45vp. The website does not give any usfull info for prop sizes and/or rpm. I am wanting to run this engine with the q500 jett pipe on a GP viper. Does anybody have any experience with this engine so i can get a little usefull info. 

Jim Oliver

My Feedback: (1)

SkooterII,

This link doesn't show your exact combination but should give some direction, maybe:

http://www.rossienginesusa.us/SGME/R...structions.pdf

Jim

skooterII

Thanks Jim, I have looked over this info before and it gives me a good idea for the stock engine. Not really sure if there is any difference between a 27r45 and a 197r45 other that the distributers. Axe with the 27r45 and SG with the 197r45. Any how i am really wanting to know what kind of performance gains the vp mod will give the engine. I can not find any info on rpm/prop number with the vp mod. So i was hoping somebody might have some experience with the vp mod.

Jim Oliver

My Feedback: (1)

When I talked with Sahak about the VP mods, he told me to expect a 20% rpm boost. That was lots higher than I expected.
If accurate, that would put the Rossi well into the Jett performance range.

Jim

bob27s

My Feedback: (19)

The 14,250 ground rpm shown there is right in the meat of the jett-stream tuning band. For ground rpm, that is perfect. For flight, you would want to set the needle on the rich side of peak rpm down about 600-800 rpm. So figure on 13,500 for launch.

Once in flight, it would unload another 500-800 rpm or so above that ground peak and it will need the extra fuel.

It is not worthwhile worrying about rpm variation of +/- 300 rpm or so - all engines will do that based on temperature/humidity/altitude, etc. Very common. Get a good reference rpm by running the engine on the test stand a few times, and you will have an idea of where it should be. For flight, just find the peak for that given day, back it off as noted, and fly it.

Bob

speedracerntrixie

My Feedback: (29)

I would have to call that VERY optimistic LOL. Scooter, I have been running the .45VP with a 10MM carb in warbird racing for 2 seasons now. The best props are the APC 9X7 sport and the 9.5X7 pylon prop cut down to 9.25". I run the same muffler as you and 15% nitro and Enya #3 plug. This is the setup I have finalized with after a good 6 months of testing fuel, plugs and props. One thing that will really help wake up the engine is to take off .025 from the top of the exahust port. Mine is a little funny as with the stated combo it actually hits the pipe on the ground. Thinking this was an indicator that too little prop was being used I put on a prop with just another .5 pitch and lost speed. But try the 9X7 on your Q500 I think you will like it. A Q500 has about the same drag as my warbird but I carry another pound.

skooterII

Thanks for the info i will deffenently keep the porting tip in mind for a few extra rpm. Im sure this engine will be plenty to have fun with on a q500.

energyman

My Feedback: (2)

Thanks Bob.

Good explanation. Ihave experienced this with most engines as I do a lot of test stand running testing various props, fuels, etc. The Rossi performs very good in the air set down about 600-800 rpm from peak and performs good in the air with no leaning in the vertical maneuvers. Good pressure from the Jett Stream also helps. Now I just have to wait for Rossi to respond to the idle needle/spray bar issue.

Danny

energyman

My Feedback: (2)

I thought I would reopen this thread due to prior interestregarding the solution Rossi had in solving the 10mm carburetor issue. I received three new idle needles from SG on Monday. I tested all three carbs on the 60LS with an APC 11x7, Omega 5% (10% and FAI blended, all I had), and the Jett Stream 60-90 muffler. All carbs functioned much better in the idle and mid range transition to high speed.

I plan toinstall the carbs on an engine currently on a plane and fine tune in the air.

I have enclosed a picture withboth the old and new idleneedles side by side for comparison. The new needle is2mm longer and appears to have less taper. This seems to be a good solution.

Danny

speedracerntrixie

My Feedback: (29)

Danny, thanks for the update. I will have to order a new needle when I order a few other things. Not sure how much that will help as Ihave decided that to be competitive in my class I will have to go to a YS 4 stroke. Did you notice that he is selling the 10MM cars on E pond for 59.99? I'm wondering why you are running such a small prop? I tried mine with a 11X8 APCand it fell off the backside of the pipe. What ended up working best for me in my application was a 10X10 APC trimmed to 9.5". I do think my header was too short though and am replacing it with a full length header and then I will try an 11X10. If that dosent get me into the speed range, its a call to Verano to order a YS 115.

stuntflyr

Hi Speed,
Can't you just increase the total pipe length by cutting a longer coupler?
The exhaust doesn't care if it's a full header or a rubber coupler.
Chris...

energyman

My Feedback: (2)

SpeedRacer,

I use the engine primarily on a classic pattern plane. Thepower band for the JS-90 is 13,000-17,000 rpmaccording to the SGME web site. I also have another LS60 on a sport plane using an APC 12x6 which loads the engine down a little more, but stillfalls in the mufflers power band. The 11x7 was turning 14,300 rpmTuesday. According to Bob27s in a prior post, the 11x7 is in the proper range for the JS-90. I have not tried the engine on a full length tuned pipe, but would like to in the future so I can evaluate how a larger prop will work with the LS engine.. However, the ability to bolt on the Jett mufflersince it'sa one piece unit is a nice setup. You just have to prop the engine to operate in the muffler's power band.

I have tried an older Rossi 60 on a Mac 10cc pipe with full length header and have found what you described; the 11x7 does not have enough load to achieve max rpm without cutting the header. I have resorted to running an APC 11x9 on this setup with good results at 13,000 rpm. This engine has an 8mm carb.

I bought two of my spare 10mm carbs the way you mentioned to be used on older Rossi's. Now that they work, I can proceed.

Danny

speedracerntrixie

My Feedback: (29)

Chris, I think that would be a great idea on a test bench but with the pipe being enclosed with minimal airflow I am afraid of buring through the coupler and spewing gunk all over the inside of my airplane. As you can see from the pic, it is tight.

Danny, I'm glad you shared that info with me. I'm not 100% sure what Rossi I have but I do know it has more stroke then the first one I had. If I can get just a little better then yours with the 11X9 and a 10mm carb I think it will get the one second per lap that I need.