Search found 32 matches

by GarethJ
Wed Feb 07, 2018 8:13 pm
Forum: Events and Racing Seagulls
Topic: Modified 102
Replies: 32
Views: 12214

Re: Modified 102

Neither would I! Even if you don't do a particularly good job of it ( :oops: ) it's not what I'd call donkey work.

Jon, if you're reading this as a guest, good luck with the screaming 102. Maybe when it's all done and running, you'll let us know, I'm sure it would be interesting!
by GarethJ
Mon Feb 05, 2018 6:39 pm
Forum: Events and Racing Seagulls
Topic: Modified 102
Replies: 32
Views: 12214

Re: Modified 102

Maybe you are thinking of the engine with the the honda crank over in the other thread. Don't think I've posted anything crank related here. Either way, you'll need a reasonable lathe as a minimum to do a similar swap.
by GarethJ
Wed Jan 24, 2018 12:34 am
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

No, it's not too too bad. But bad enough. I put a clock on the flywheel lower lip the other day and it had about 15 thou of wibble. Whoever removed the crank from the original motor must have duffed up the centre drilling on the end. I tried to get it true but must have been off a tad. Amplified by ...
by GarethJ
Mon Jan 22, 2018 7:35 pm
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

Managed a test on the pond with tachometer this afternoon. (A test on the pond just involves clamping the motor onto a jetty and seeing what it will rev to) With a 2hp Yamaha prop, 7,1/4 x 4, It will do 5750 RPM. Some fluctuations above but I suspect cavitation With a prop of unknown manufacturer, 8...
by GarethJ
Wed Jan 17, 2018 9:52 pm
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

Following a nice chat with a forum member this morning, I riffled through some of the drawings I did and found the bearing details. IMG_20180117_204006-01.jpeg You can hopefully make out the layout. Two questionably dainty ball bearings on the upper end and a single medium sized one at the bottom. F...
by GarethJ
Wed Jan 17, 2018 11:16 am
Forum: Events and Racing Seagulls
Topic: Modified 102
Replies: 32
Views: 12214

Re: Modified 102

Measuring everything is well covered in this book; http://www.google.co.uk/url?q=http://www.amrca.com/tech/tuners.pdf&sa=U&ved=0ahUKEwjViM_H397YAhVEF8AKHZEUD-cQFgg6MAc&usg=AOvVaw1SEkbdgSpDIb65I9G7tFUB Including the primary compression ratio, which is easy to achieve with basic tools. It's worth read...
by GarethJ
Sun Jan 14, 2018 8:07 pm
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

I have been tempted to doctor the 416 but it's my only one and I'd like to keep enough bits to rebuild the silver in original state if I can. Plus something doesn't quite feel right to go boring out the fuel metering device that relies on Venturi to work properly. I'm sure an 18mm carb will find it'...
by GarethJ
Sun Jan 14, 2018 7:27 pm
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

Its an old town camper and isn't actually mine but it's all I have access to at the minute. It's a nice canoe and doesn't deserve to be treated as harshly as we have but my goodness is it tough! Ah, right, I can see that a quicker 'box would have advantages, I wasn't actually aware there was a 2.1:1...
by GarethJ
Sat Jan 13, 2018 9:07 pm
Forum: Events and Racing Seagulls
Topic: Modified 102
Replies: 32
Views: 12214

Re: Modified 102

You might struggle to find a lot of space to take up with "stuffers" to compensate for any case volume enlargements. Most of the area that looks like space is needed to clear the clunky big end shell bolts. Using up almost all of this space on my "97" brought primary compression to where I thought i...
by GarethJ
Sat Jan 13, 2018 8:50 pm
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

Thanks for the positive comments! Don't hold back asking questions to me, if I know the answer, I'll be happy to divulge. My test (well, only) vessel is a 17ft canadian canoe. Not a racing boat (hull speed and that) for sure but quite fun. Developments are as follows. -standard, good silver seagull ...
by GarethJ
Sat Jan 13, 2018 12:27 pm
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

Haha, the benefit of hindsight!

Maybe that's an idea for another day. To be honest though, while the little end setup I've got there took a bit of planning, actually doing it was straightforward and inexpensive. We'll see if it proves to be sturdy enough or not!
by GarethJ
Sat Jan 13, 2018 11:10 am
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

PS,
I think the rod was 75mm as per this chart for the Lead50/vision.
http://www.mitaka.co.uk/MDP.htm

Your 76mm walleroo/spx50 is listed just below. May have been a better choice!
by GarethJ
Sat Jan 13, 2018 7:30 am
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

First and foremost, this is a fun tinkering project. No budget for fancy pants racing parts. I've spent a bit on one off tools and a few tens of pounds on second hand eBay bits, bearings and propellers but total spend would be less than one of those cranks. Even then, I'd be limited to just roller b...
by GarethJ
Sat Jan 13, 2018 12:00 am
Forum: Events and Racing Seagulls
Topic: 97cc Seagull
Replies: 38
Views: 11009

Re: 97cc Seagull

I did do quite a bit with the port timing but my notes are a jumbled mess again so I'd need to do another set of measurements/port map to be sure. Compression ratio was last calculated at about 10:1 (6.5:1 corrected) but I know I changed head gasket plans since then so will be slightly different. Re...
by GarethJ
Fri Jan 12, 2018 11:47 pm
Forum: Events and Racing Seagulls
Topic: Modified 102
Replies: 32
Views: 12214

Re: Modified 102

I just read the interesting thread this post stemmed from. I would say that in my limited experience of welding stuff, filling the head might be achieved by "cold" arc welding with nickel rods. Time consuming but you eliminate the risk of warping. You'd need to protect the cylinder sides though.