MNSBR: Super Grom Build - MNSBR

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Super Grom Build

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Posted 02 April 2018 - 09:50 AM

View PostJim Hubert, on 02 April 2018 - 09:26 AM, said:

I once tried to break a bead by using a vacuum pump -- it did not work. But that would get all the air, and any moisture, out.


:lol2:

I used 3 wood clamps to break the beads on the Grom tires :D
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Posted Yesterday, 08:36 PM

How stable are Groms once you get past 65mph?
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Posted Today, 07:51 AM

View PostnOOb, on 18 April 2018 - 08:36 PM, said:

How stable are Groms once you get past 65mph?


Compared to a full sized bike, they're twitchy at any speed. But when I'm pegged at 60, it's confidently planted and you can still do the handle-bar-shake and get away with it fine. Even though it's planted, it's still a short wheel base that reacts quickly to small inputs. I can easily and quickly dip in and out of lanes with confidence.


Once I put suspension on, front and back, it's MUCH(!!!!!) better. I shouldn't have a problem with it holding higher speeds. If I had stock suspension, I would not be adding power. Stock suspension would be very dangerous maneuvering at high speeds. The faster you go, the more potential for higher forces on the suspension that stock is equipped to handle in the least. In a quick-brake scenario, the stock suspension is garbage and bottoms out immediately. If you hit a horizontal crack mid-corner, even at 30mph, the front and rear bounce and cause you to fade out. Stock suspension is very VERY shitty. For a competent rider, suspension should be one of the first upgrades. For plain jane commuting, stock will get you by.
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#19 User is offline   Kent Larson Icon

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Posted Today, 09:32 AM

View PostnOOb, on 18 April 2018 - 08:36 PM, said:

How stable are Groms once you get past 65mph?


Never had any concern at any speed the wife's Grom could manage.
A few times I've been in full tuck and drafting I-94 traffic at 70-75 indicated with everything feeling smooth.

Later,
Kent Larson in Woodbury
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Posted Today, 10:02 AM

70-75? That must not be stock gearing... what does a Grom top out at (redline in 4th gear)?
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Posted Today, 10:58 AM

View PostKent Larson, on 19 April 2018 - 09:32 AM, said:

Never had any concern at any speed the wife's Grom could manage.
A few times I've been in full tuck and drafting I-94 traffic at 70-75 indicated with everything feeling smooth.

Later,
Kent Larson in Woodbury


If you play the full tuck and draft game, stock gears will always be rev limited at 73 indicated. Which GPS would tell you about 70 or maybe 71mph

I'm geared from stock 15/34 down to 14/37 (-1/+3) which puts my rev limited max GPS speed at 61mph.

A stock Grom with no draft, wind, or hill can aerodynamically limit at about 60-62mph on stock gears. Since 99% of my riding does not put me in a draft or highway situation where I need speeds higher than 61mph, setting my gears at -1/+3 lets me use the entire rev range up to 9500rpm to get to top speed of 61 It's all the power the Grom can offer across the functional speed of the Grom. It's the ideal ratio for best top speed and acceleration, excluding scenarios with draft, wind and hills.

When I get my new ECU, I'll have an increased red line that goes from stock 9,500rpm to 12,500rpm. Not sure if I'll still be making power at 12k+, but we'll see I suppose. I'm going to stick with the gearing I have now and try it out with the new engine build. I'll be going from 8hp to ~15-16hp so these gears should be very very strong. I'm sure I'll end up going higher eventually, but I won't know till I try it.
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