Montesa Impala Sports
MONTESA IMPALA SPORTS
CYCLE WORLD ROAD TEST
VERY EARLY in CYCLE WORLD'S history, which is to say about three years ago, we were brought our first Montesa motorcycle for road test. It was in many respects a curious-looking contraption, with spindly 19-inch wheels and an engine/transmission assembly that appeared to be an almost infinite number of castings, pressings and machined bits all bolted together helter-skelter. But the quality of workmanship was of a very high order, as were the braking and handling characteristics, and its performance was somewhat out of proportion to the Montesa’s engine displacement.
Today, the Montesa 175 Impala Sports, which is a direct development of that original test bike, still has the quality, braking and handling; but the performance is now incredibly disproportionate to displacement. Of course, in light of present knowledge this seems no more than proper, for these things can be said of all the motorcycles in the Montesa line.
The truth of this was hammered home in no halfhearted fashion during our test of the latest 175 Impala Sports, for when we arrived at Riverside Raceway, where the bulk of the testing was to be performed, we were presented with what appeared to be at least two of every motorcycle Montesa Motors, the distributors, bring into this country. We mention this in hope that you will forgive us if we make occasional reference to Montesas other than the Impala Sport that is the principal subject of this test.
The 1965 version of the Montesa Impala Sport has a frame essentially identical to that of our first test machine, and the same 19-inch wheels, but in all other respects, Montesa has come a long way with their touring bike. For one thing, the engine is virtually all-new. The bits-and-pieces look is gone, and both crank and transmission assemblies are housed in “unit-construction” cases. Full-circle flywheels are still featured, and the connecting rod, which has an unusual (for two-strokes) I-beam shank, is fitted with double-row roller bearings. The crank’s mainshafts run in ball bearings. In the 250cc Montesa Scrambler engine, the small end of the connecting rod has a needle-roller bearing, but to date a plain bronze bushing has proven entirely satisfactory in the less highly-stressed 175cc engine.
From the standpoint of a “tuner,” the Montesa engine is particularly attractive because the cast-iron cylinder liner is removable. This enables one to pull the liner and, with everything nicely exposed, do a really good job of altering the porting. Anyone who has tried to trim the transfer ports when everything is cast in a single piece will appreciate what a fine thing a removable cylinder sleeve really is. Of course, it is also true that heat transference between liner and cylinder is better when the liner is cast in, but the difference is not so great as one might imagine. In any case, the Montesa’s aluminum cylinder, with its deep, close-pitch finning, will insure good cooling.
The Montesa engine is virtually unique in being fitted with (as standard equipment) Dykes-pattern piston rings. The upper ring (two of these L-section rings are used) is right up at the top of the piston, with no land above, so the fire is stopped before it can reach any part of the piston skirt. This top ring is chromed; second coated to prevent scuffing.
In its original form, the Montesa had a chain-drive primary, but on the new unit-constructed model the clutch is coupled to the crankshaft through helical-cut gears, which have a reduction ratio of 2.65:1. Interestingly, the clutch has all-steel plates, 13 of them, with no linings at all. Apparently, the viscosity of the oil on the clutch plates is enough to “glue” the plates together, when engaged, and transmit the torque. We have seen plates from well-used Montesa clutches, and there is little sign of wear, which speaks well for the service life of the device. And, we can testify that the clutch does not slip, and engages with commendable smoothness.
Somewhere in the process of development, the original carburetor and its steeply-downdraft manifold have been replaced. Now, the carburetor is mounted more or less level, and there is no longer the tendency for fuel to dribble down from the idle-mixture passages and flood the crankcase. Also, the new carburetor, a Spanish-made Amal, has its main jet inserted from the side, and it is now very easy to make jet changes.
One of the Montesa’s best features is its forks, which give equally good results on both pavement and dirt models. The springing is right, and the fork’s damper elements, which are mounted down in those odd looking extensions below the axle-eyes, give excellent control of the wheel movements. Kim Kimball, who heads Montesa Motors, says that there were some complaints about fork-bottoming, but modifications made to the springs have taken care of that.
New on the 1965 Impala sports is a double-leading shoe front brake. Drum diameter remains the same, at 180mm (7.09"), but now of course the rider gets selfserve action from two shoes (instead of one) to help him stop the bike and the backing plate has a big air-scoop cast in; a small hole bored in the opposite side of the backing plate gives the air an exit. It may be that under racing conditions, on a difficult circuit, this brake would be worked to its maximum; normal, or even very fast touring will not have much effect. We pushed the Impala Sports around Riverside Raceway as fast as it would go, and were unable to get the brakes even warm.
During our “hot laps” session with the Montesas, we re-acquainted ourselves with the bike’s fine handling qualities. This is one machine that goes where it is aimed, and is rock-steady in the corners. Being touring bikes, and lacking an over-abundance of clearance for lean in cornering, we could not give them a real road racing test. However, we can tell you that the touring rider can feel perfectly confident about pulling the Montesa over in a turn until parts begin to drag (the stand will contact the pavement first).
Having the full length of Riverside Raceway’s back straightaway available, we decided to take a few top-speed runs with the Montesas. The results were staggering. The Impala Sports, in gentle, touring trim, with muffler in place, made run after run at 89 mph, varying only lOths one way or the other. What made this little demonstration all the more interesting, and impressive, was that Dan Gurney’s (yes, he was out there with us, participating in the fun and games) own Impala Sports was running through at almost exactly the same speed — and that particular Montesa has been flogged to a fare-thee-well for many moons.
Also on hand at Riverside was an Impala Super Sport, which is an Impala Sport with a 30mm carburetor, a scrambler cylinder head that gives a 14:1 compression ratio, and a “tuned” expansion-chamber exhaust system. This little dandy, which would be entirely suitable to ride on the public roads except for the rather noisy exhaust, made a best run of slightly over 103 mph. A bit of on-thespot tuning, and some fiddling with gearing was required to get it up to that speed, but the fact remains that it did the job. With this sort of performance, it is little wonder that the Montesa 175 has done so well in production-bike road races. Some of the Montesa Scrambler’s winning ways were explained during our “Montesa-Day” at Riverside Raceway, too: one of these, carrying gearing that is actually used in some of our Western desert-scrambles events, ran through at 88 mph.
In all, there are a lot of good things that can be said of the Montesa, and we have only three complaints: we really do wish that the company would change speedometers as the present instrument is marked in kilometers per hour, when it should be mph, and it is scandalously inaccurate as well. We would also like to see some change made in the kick-start lever, which folds too far forward and is awkward to pull over into a position where it can be used. Finally, we think a full 250cc engine for the touring Montesa is long overdue. The company already has this for their Scrambler, and while the 175cc engine does a remarkable job of pushing the Montesa Impala Sports down the road, anyone who knows of the existence of the 250cc unit will wish they had it. They would then be able to “smoke-off” 40-inch twins, instead of having to content themselves with humiliating an occasional 21-incher.
For the rest, it is hard to find fault with the Montesa. The overall fit and finish is impressive, and it has a lot of nice touches like the aluminum-alloy wheel rims, and polished engine cases — which contrast nicely with the matt-black cylinder and head. As we said at the conclusion of our original Montesa road test, we are inclined to doubt that money will buy the two-stroke fancier with a yen for something different any more satisfaction, or fun, anywhere. •
MONTESA IMPALA SPORTS
SPECIFICATIONS
$615.00
PERFORMANCE
