claytonrduvall

maybe some one can help me out here. i have been looking for this motor now for a while and have been unable to find it any where, non of my local hobby stores can get and and i have looked online for a while now with no better outcome , if you can help that would be great. thanks clay
http://www.os-engines.co.jp/english/...e/marindex.htm

sorry could not get a picture to work right!!

MAX-81VR-M ABC

Expressly For power-boat racing

Displacement
13.01cc(0.794cu.in) Output
4.2ps/22,000r.p.m.
Bore
26.0mm(1.024in.) Practical r.p.m.Range
2,500-25,000r.p.m.
Stroke
24.5mm(0.965in.) Weight
914g(32.3oz.)

piper_chuck

My Feedback: (12)

It's discontinued, not just in the US, but worldwide. I tried some of my Asian contacts and they can't get them either. Occasionally one will come up on eBay.

claytonrduvall

um , whats another motor that is similar to it, any ideas. thanks again clay

Jerry Dunlap

I think CMB makes an .84 engine.

JD

gooycheese

ummm you could try this sight they seem to have some bigger nitro motors.

www.rocketcityracing.com


paul

claytonrduvall

any body ever heard any thing about the ops .80 or the k&b .80 motors, i just found those and they looked good, did not know how they where any ideas . thanks clay

piper_chuck

My Feedback: (12)

I've run the .67 version of the OPS. Ran great until it threw the rod, which also took out the piston and sleeve. The .80 size is also supposed to be good. The CMB that Jerry mentioned would give more power, but it all depends what you want to do.

Ron Olson

My Feedback: (1)

The .80's have had the rod problems also. One of the guys that I run with bought 2 of the .80's and needed the extra one for parts. When they're between breaking rods, they will scream. I've been hosed down plenty of times launching his boat.

claytonrduvall

then what motor would be a reliable yet good motor to run around the .67 to .90 range. thanks clay

Ron Olson

My Feedback: (1)

Try a MAC if you can find one or a CMB.

claytonrduvall

wow , i found a cmb and about fell voer wit hthe price , but for the money which one would be the best, also i am kinda new to nitro engines

Ron Olson

My Feedback: (1)

Wait until you have to buy a 24-volt starter to fire it up plus the 2 batteries needed for that. I don't even want to get into the cost of the fuel but you'll want to get it by the case.

claytonrduvall

i was just looking on ebay and the cmb 7.5cc has just as much power as the ops .67, and for hte price which one do you think is a better motor, clay

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1

Ron Olson

My Feedback: (1)

I don't know where that guy gets all of his engines at as he's had some older MAC .45's up for auction also. you can tell them by a reversed 4 in the .45 .

Let's start fresh here. You're looking for a nitro boat, right? What type of boat do you want and what size? Do you plan on racing or just messing around with it?

claytonrduvall

wel ron , i have ordered a 31 inch deep vee boat from barmstomer boats,( i like the idea that he makes all of his own boats and each boat is a little bit different), he said that he sells them with a 7.5 cc nitro motor in them and i asked him if he went bigger would it work out and he said yes, so the smalest motor that i was looking for would be a 7.5cc, i do not plan on racing this boat i just want to build a very fast boat. i like to build boats , i have built a few electic boats from the hull up ,they are manily just for looks and not for speed ( tug and fishing boats) , i also have built a few rock crawlers, which are really fun, again very slow. just was looking for some thing fast and reliable. hope you can help thanks clay

Ron Olson

My Feedback: (1)

A good 7.5 will make the boat run plenty fast. A .67 would be more than enough. Usually you don't need more than a 3.5 in a 31" boat.

claytonrduvall

ok chossing hte 7.5 which motor barnd do you thikn would suit me best

Ron Olson

My Feedback: (1)

If you want fast, go with the MAC if you can find one (Andy Brown and Co. are changing over to an all new line of engines) or a CMB. Those two are the most popular in the go-fast crowd.

claytonrduvall

i looked at the macs and i think that they looked good, but then what harware system would you use on that , i would likto use a surface drive if possible. thanks agian

Ron Olson

My Feedback: (1)

I really like Speedmaster hardware at www.rossisales.com , a little pricy but worth it.

claytonrduvall

a lright thanks for the info i hope to talk to you more later on , you are very helpfull, thanks alot clay

Jerry Dunlap

Sticking a 7.5 engine in a 31" vee is way more engine than that size hull can handle. Just my opinion. But, I've only been r/c model boating for 42 years so what do I know?

JD

Ron Olson

My Feedback: (1)

Jerry, I wouldn't put more than a good .21 in it either but here's a picture from Tim's site of what I think is the hull in question. He won't mind the publicity.

claytonrduvall

so you guys now think that a 7.5 is over kill for this boat, and i should go with a .21, whats the main difference betwwen the two sizes of motor( besides power and a little weight), what would be bad about it i guess i should ask. thanks clay

Ron Olson

My Feedback: (1)

I'd say that a .45 is the maximum that I'd drop in there, any more would be uncontrollable. That hull size is best suited for a .21 .
Seeing how you already ordered the hull from Tim, I'd go with a good .21 as it will be a lot cheaper in the long run for not only the engine and hardware but the fuel costs. If you don't already have an electric starter you can look for one with a pull-start. A decent setup will put you in the mid to high 40 MPH range with no trouble.